Electron Exile

reminisce about bbc micro & electron games like chuckie egg, repton, elite & exile

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davidb
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Electron Exile

Postby davidb » Thu Nov 17, 2016 10:30 pm

Until recently there weren't many videos of Exile on the Electron on YouTube, and those that were there didn't really show very much of the game. Inspired by this play-through for the BBC version, I've just completed my own play-through for the Electron version.

I'm thinking of writing my thoughts about the game in this thread. I'll probably also make some comments on this particular solution to explain some unconventional aspects of it. Comments and queries from others are welcome. :D

Edit: I should note that I used John McHugh's solution on a number of occasions, though I only got some of his tricks to work. ;)
Last edited by davidb on Fri Nov 25, 2016 12:40 am, edited 1 time in total.

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Re: Electron Exile

Postby sydney » Thu Nov 17, 2016 11:35 pm

:shock:
=D> =D> =D> =D> =D> =D> =D> =D> =D>
That must have taken a long time! Well done. Once I finally (if I ever) get to elite I'll be having a go at exile - probably the beeb version though.

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Re: Electron Exile

Postby daveejhitchins » Fri Nov 18, 2016 9:13 am

Never mind the time taken - what about the Patience! :shock: =D>

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Re: Electron Exile

Postby davidb » Fri Nov 18, 2016 12:44 pm

The time shown in the last video is 12 hours 39 minutes and 12 seconds, though there were bits that needed doing a few times. I didn't play it all in one sitting! :lol:

If you know where everything is then it takes a lot less time than it would if you were exploring all the areas in the game trying to find things. Thank goodness for Elkulator's save state feature! :D

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Re: Electron Exile

Postby Dave_E » Sun Nov 20, 2016 9:18 pm

I actually completed it all on an original Electron without save states following the solution that was published in EUG. To use the save game feature you had to BREAK out of the game and save it, so an already looooooooooong game to solve was further complicated by having to re-load it from tape (taking another ten minutes) every time you saved your position for safe-keeping.

So much wasted life... ;-p

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Re: Electron Exile

Postby davidb » Sun Nov 20, 2016 9:57 pm

Agreed. I would really have liked a disk version back in the day, just like the one from Every Game Going which I used to bootstrap my attempt. I'm now hacking around in Elkulator snapshots to explore how the map generation works.

I should write something reflective about the game but have been recovering from a cold, so I haven't been in the best frame of mind to do something like that. I can, however, make some notes about my play-though.

I "cheated" and used the pistol to get the grenade turret to send the icer and protection suit through a teleporter early in the game, making some things easier to fight and other situations easier to deal with. You can also throw wasps under the door near the start to achieve the same result but it's a bit more hit and miss.

I spent some time blasting through doors to the right of the windy tunnel area because I wanted to try the "correct" way of creating slimes to Coronium boulders outlined in this article. However, it seemed to be difficult to get them to appear and leave their nest, so I gave up and used the "cheat" where you sneak them past two bushes in the area to the right of the windy tunnel. At least it gave me the chance to obtain the plasma torch. The sneaking trick was used again when transporting Coronium boulders to the door blocking the way to the mushroom immunity pill.

My plan was to race to the end, rescuing the crew members and retrieving the Destinator while avoiding Triax and the two remaining clawed robots, but Triax was relentless, so I had to spend some time killing off the robots and trapping him at least twice. The last part of the game is just brutal to play and I didn't enjoy it at all. :(

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Re: Electron Exile

Postby davidb » Tue Nov 22, 2016 5:01 pm

I thought I'd write something about the game. Warning: Contains spoilers!

It's difficult to appreciate today how remarkable Exile was when it was released for the Acorn 8-bit machines in 1988. It's also difficult to describe why it was so remarkable at the time. I think it was due to a combination of things that came together to produce a game that appeared to transcend the capabilities of the hardware it was running on. The polished nature of the graphics and sound, the freedom of movement, the application of physical concepts to gameplay, the variety of objects and scenery, the apparently complex behaviour of the creatures in the game, and the inclusion of set-piece events - all these contribute to what was a paradigm shift for 8-bit games, and possibly even for gaming in general. There were games before Exile that had some of these qualities but none had put them all together in one package.

The Edge magazine retrospective about Exile talks about "freedom" being the defining quality of the game - I think this can be attributed to the game's construction around a well-designed physics engine operating on a "sandbox" model of a game world. Earlier arcade adventures had puzzles and limited rules about how characters moved. In contrast, Exile has physical rules that apply to everything and a set of puzzles that are consistent with those rules. This makes it something the player experiences rather than plays, at least until you reach the limitations of the game engine, and contributes to the different feel that the game has compared to traditional arcade adventures.

It can take a while for the player to appreciate the depth the game has. However, the start of the game exposes the player to many of the innovations mentioned above: motion that follows physical laws, particle and wind effects, object-based gameplay and limited artificial intelligence (AI) for the creatures encountered. On the Electron the map jump-scrolls when necessary, but so quickly that exploring the planet is liberating compared to the many other contemporary arcade adventures with screen-by-screen gameplay. After a while you stop noticing the coarse level of the scrolling and get on with playing the game. Entering the caverns beneath the surface reveals a range of creatures with different behaviour, including robots and turrets with various kinds of weapons, as well as a classic arcade adventure fire-and-water puzzle. If Exile had only included this area it would have been impressive enough as a technical achievement - so much is crammed into this area that it seems artificial, and it is, but that's a discussion for later.

The depth of the game opens up when the player leaves this initial area to encounter a second area where more of the objects they need to collect are stored. This area, based around a vertical shaft that funnels air flow upwards, contains more creatures. However, while some of them are new, others are different types of the ones encountered in the first area, revealing the flexibility and reusability allowed by the object system in the game. The air flow in the vertical shaft itself is unlike what you might expect from a game of this era: gusts of air whip dust particles upwards erratically rather than in a steady stream. In this area we encounter underwater creatures, radioactive rocks and processes that convert creatures of one species into these radioactive Coronium rocks. We also start to encounter the arch-villain for the first time, and we encounter lots of mushrooms that incapacitate the player's character. These are used as a way to restrict access to parts of the map, but have an additional use in the production of energy cells that the player will need in order to prolong their mission. The energy economy of the world dominates much of the middle and end sections of the game. Early in the game, energy cells can be obtained fairly easily, but these are only present in the first and second areas of the map.

Another progress-impeding class of objects are the bushes which, early in the game spawn creatures like birds, but later will "suck in" or "blow away" the player's character and other creatures depending on their respective types. These occur throughout the rest of the game and, apart from the one near the radiation immunity pill, they appear to have been used to funnel the player through certain areas of the map, particularly when their character is carrying Coronium boulders. At this point, the freedom the player experiences is limited. It's true that, on a large scale, their freedom has always been limited by the restrictions of the map, even while on a smaller scale their character can fly around mostly unhindered. However, the restrictions on routes that the player can take with Coronium boulders from the second area to the first is reminiscent of many classic arcade adventures. That the "easiest" route is one where it pays to exploit the limitations of the game engine is an unfortunate way to reinforce the impression that the player is solving some sort of logic puzzle rather than something that emerged from the geography of the world itself, even if the geography may have been the inspiration for such a puzzle.

As the second area is explored and necessary items are found, including two Coronium boulders, the player gains access to more parts of both the first and second areas, eliminating enemies and finding allies: one of these is a friendly pet that can help with the retrieval of items, the other a robot that can fight alongside you and help recharge your energy supply. The robot, Chatter, shows off the versatility of the game engine, behaving like other flying robots yet with his own type of weapon, the ability to produce energy cells, and a fail-safe state that causes him to switch off rather than be killed. In addition to this, the player controls the mode he is in using two whistles, making him a rather complex character. Interestingly, the player is not the only one who can use whistles to control him, as they may discover later.

The third area to be explored is accessed from the first area via a stone door which must be blasted through using the Coronium boulder to create a small nuclear explosion. More variants of existing creatures appear in this area, plus several items that the player is still expecting to find. A couple of additional items with useful properties, protecting the player's character from the effects of mushrooms and fire, make unexpected appearances. However, the mushroom immunity pill is located in such a way that forces the player to reuse their skills with Coronium rocks in order to obtain it. Some elegant solutions to puzzles like these have been suggested but, by this time, players may have been getting tired of exploring this game mechanic which seems like it was only used twice to slow players down.

I hope this was mostly coherent. I'll add more of my thoughts to another post, and may revise this one again later.

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Re: Electron Exile

Postby trixster » Tue Nov 22, 2016 9:02 pm

Amazing work David, thanks for the fascinating post and the superb videos. I've never seen exile on the electron. I assumed that other than the colours it was identical to the BBC but it's interesting to see the minor but noticeable differences.
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Re: Electron Exile

Postby Rich Talbot-Watkins » Tue Nov 22, 2016 9:19 pm

Great write-up David! It still amazes me, even with the disassembly in front of me, how this worked on the Beeb, let alone the Electron. And the flawless engineering is matched by the impeccable game design. These days it's hard to find examples of standout games (for me, the next one to come after Exile was probably Doom, in terms of paradigm-shifting games), which makes it all the more impressive.

And it's true, one of Exile's most appealing features is its "sandbox" world. I spent so many sessions not even attempting to advance in the game, but just playing with the characters in the first cavern, leading birds over to the killer robot with the homing missiles and so on. Just the explosions and the sound effects were satisfying enough to get plenty of fun from playing about with it. And I remember it was almost scary at times - hidden nasties hiding in pots or bushes which would suddenly appear with an abrupt sound effect could make you jump. That it was able to create that kind of atmosphere given the limitations of the platform is nothing short of remarkable.

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Re: Electron Exile

Postby davidb » Tue Nov 22, 2016 10:34 pm

Thanks for the feedback! :D

Beyond the audiovisual differences, which of course aren't trivial, I don't think there's so much of a difference between the BBC and Electron versions, though I have to say that I'm working from the cracked 5 1/4" DFS disk version from Every Game Going. Looking at the existing BBC disassembly to try and figure out how the procedural map generation works, what struck me was that the code was more-or-less the same, only at a slightly different position in memory.

I haven't talked about the map generation yet because I flip between being impressed and unimpressed with it! :o A lot of the early parts of the game are pre-built, which is a disappointment, and I have to spend more time revisiting some areas to get excited about it again. Maps like Bill Carr's excellent screenshot map help to get an overview of the scale of the accomplishment.

I'm not sure if I should start a new thread for this, but I've been experimenting with adjustments to the code to switch off various parts of the map generation code then going back later and creating videos of the results. The first one is quite simple, removing the Pericles and turning a few other features off, but it is interesting because it shows how the planet surface is handled - there's a row of solid blocks with only one missing at the far left of the map. I've made another that shows what the map looks like with the artificial structures near the surface disabled, and a third with many deeper structures also disabled.

It's surprising what's removed and what's retained! For example, it's not surprising that the structures in the first cavern are artificial, but even when they're removed, the doors and turrets at the cavern's floor are still there because they lie on a row that has a horizontal passage and those tile types appear to fall out of the algorithm naturally. Another example is the cave with the wasp nest and grenade, near the entrance, which appears to be artificial. However, the nest is a feature of the algorithm, again on a row with a horizontal passage but, without the cave carved out of the map, we also find a locked door on that row! You can see the grenade still appears, though now it's embedded in the rock.

wasp-nest-with-unexpected-door.png
Wasp nest cave without the cave!
wasp-nest-with-unexpected-door.png (8.68 KiB) Viewed 131 times

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Re: Electron Exile

Postby Rich Talbot-Watkins » Thu Nov 24, 2016 11:39 am

I saw your latest video where you made a small change to the map generation algorithm - interesting stuff. Funny to imagine that there's so many possible worlds it can create. Still don't really understand how it decides where to place creature spawners and this kind of thing though.

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Re: Electron Exile

Postby davidb » Thu Nov 24, 2016 12:10 pm

Yes, I forgot to link to the modified map video. I had thought that some nests/bushes were simply placed by the algorithm but that wouldn't deal with the ones that you can destroy or those with a limited number of occupants. :? I just changed a value in a table of predefined values and the game put a flying robot in the place of a door, so that's clearly not the right thing to look at! :)

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Re: Electron Exile

Postby davidb » Mon Nov 28, 2016 6:18 pm

On a subject other than the map generation, I made a video showing surprising aspects of the object system for those who have never tried any of the classic cheats for the BBC Micro version that let you choose which items Finn is carrying. I happened to choose Finn, Chatter, a crew member and Fluffy. :)

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Re: Electron Exile

Postby Rich Talbot-Watkins » Tue Nov 29, 2016 11:36 am

What is that crazy burning spaceman object in your latest video? :shock: Never saw that one before. I remember Chatter's lightning being quite a fun weapon. Also, it does crazy things if you put new teleporters into the level - no idea how it chooses a destination for them. And I remember there being an object which looked like a single red pixel and weighed a ton - never found out what that was.

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Re: Electron Exile

Postby davidb » Tue Nov 29, 2016 1:01 pm

The last object in the latest video has a type number of 0xa4 which is an index that goes way past the end of each table that describes the object. The byte it happens to access for the object's sprite is 0x05 which is close to what Finn and the crew members have (0x04), so I think it just happens to select a frame of the spaceman animation. I don't know how to find the address in memory where it happens to think the handler routine is, but it behaves a lot like water being spilt from a container. It's just that the palette looks very fiery! :D