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The Retro Asylum interview Paul Koller


Interview by PressPlayOnTape
Firstly, on behalf of myself, the Retro Asylum and our community – thanks for agreeing to talk to us today.

So let’s get started…

Why did you decide to convert Canabalt to the C64?
I’d like my games to have instant gameplay. Due to limited time nowadays I kind of lost interest in mainstream gaming where you have to invest a lot of time to get any gaming experience out of it. Indie gaming is kind of the revival of the old simple gaming experiences from my youth, but now with new interesting gameplay mechanics. I encountered Canabalt already in 2009 when the flash version came out. I immediately saw the potential for a demake. I see it as a technical challenge for me to try to convert a modern game to a vintage platform…

Why did you choose the C64 over the other 8-bit machines?
Well, I grew up with the c64, so it is the platform I know best. Also, of all the 8bit machines it has the best compromise between its technical features. In the right hands it can even today produce games that can stand proud between modern indie games.

Given the C64’s limitations did you run into any obstacles during the conversion process?
Actually not really much. In principle Canabalt is only a fast scrolling engine with some simple collisions, so it was not that hard. Although due to technical limitations some things had to go, like vertical scrolling, multiple parallax background layers, and too much shards or birds on screen at the same time. But these are mostly cosmetic so it was not crucial… One thing I did have some problem with was the procedural level generation. The building height and widths depend on things like player speed, previous building height, but also screen-width. The Flash original is widescreen so that you can look ahead. I didn’t want to vertically crop the c64 screen, so the view ahead is only limited. Still I think it works quite well…

The other “bigger” issue was trying to get it to work on american c64s. These have less CPU power per frame and therefore some things had to go to keep it all in one frame (crucial for such a game). In the end I removed the parallax background, so now you can also play it on NTSC machines! This was crucial for us, since the original author is from the states (see next question).

Have the original creators of Canabalt seen your conversion and what do they think?
Yes, we contacted Adam Saltsman (who created the original) when the game was almost finished. He was really impressed and supportive. He even suggested the name for the C64 version, and designed the artwork for the cartridge release! It seems everybody loves the c64!

Do you feel 8-bit gaming is still relevant today?
This is a difficult question. It was also asked to me after my GDC talk. Most people above 30 nowadays in the gaming or IT business grew up with a c64. So this means that everybody has fond memories of this system. Therefore you could see new c64 demakes as a kind of promotional for your new game. On the other hand, kids nowadays don’t really care about the platform they play on. I.e. if the game is fun they’ll play it on anything. You can see this at retro-events where kids play games on platforms from before they were born without problems! So in this way 8bit gaming is still relevant today…

What are you thoughts on the booming retro revival that is currently taking place?
I think this is partly fuelled by the fact that these systems from our youth are now remembered by people reaching middle age 😉 So from a nostalgic point of view. On the other hand, the recent interest boost in indie games hints back to the old days when games were simple to play and were designed by small teams.

What advice would you have for any enthusiast looking to get into old-school game development?
Just start simple and don’t aim too high. Since all this is just a hobby, keeping motivation up is very important. The advantage of the c64 is that you can quite quickly already get a sprite up on the screen and controllable by a joystick. You can then expand on that…

Since our review of C64anabalt – a lot of Retro Asylum forum members have been competing for a top score, what’s your highest score?
I’m not sure, but I think it’s somewhere close to 15000m. If you’re going to sit down for it, you should be able to beat this. Some hints to remember are that between each special building (crane, bomb, crashing building, or indoor building) there are, I think, 3-5 normal buildings. Use these normal buildings to make sure you have a correct speed (not too fast or too slow) when a special building occurs, since the bomb and indoor buildings are normally the things that kill you when you’re speed is not optimal!

Tell us a little bit about your retro collection
To be honest I don’t have a big collection. I have about 6 c64s (most as spares) and an Amiga500. I don’t really collect old HW or games. For me it’s about writing things for the old HW instead of only collecting…

Can you tell us about any future conversions you have planned
There are lots of current indie games that have interesting gameplay concepts that would work very well as c64 versions. The problem is always time of course… I’ll give a list of indie games that I’m possibly interested in converting. One of these might (or might not) be my current project 😉

Cavestory, Escape Goat, Luftrauser, Starguard, Super Hexagon, Super Meatboy, Super Puzzle Platformer, Spelunky, Tiny Barbarian, etc…

Which development environment do you use?
I use a crossassembler for compiling. I actually use 64tass, which has a very easy and capable syntax. I use a simple texteditor under windows to write the code in. I wouldn’t recommend native assemblers, since you’re too limited in memory usage and compiling times are way too long…

Can you tell us more about multiplexing sprites?
I always thought multiplexors were way too difficult to understand. But in the end it’s actually quite simple (as is everything if you know how…). The difficulty is mostly in the sorting part and not really in the multiplexing itself. I started with one of the simple ones, together with the background information from one of Cadavers rant. Then you should be able to get something running with some effort…

Would you ever consider remaking an old C64 game that was rubbish. Chase HQ for instance?
Porting a game is still quite a lot of work even if you know what you’re doing, due to having to code everything in low-level assembly. I.e. I choose my projects because I like the game myself and know if a c64 version would work, and if something like it has never been seen before on the c64. Recoding an old racing game doesn’t really fit in this…

What keeps you developing for the C64?
The technical challenges and bringing something new to the c64 that has not been seen before on the platform. As stated above I think there are lots of great game-genres that would work great on an 8bit machine, which were never done on the c64. As long as I enjoy doing it, I will continue…

What coding techniques were used for the random level generation on C64anabalt?
Actually I was helped here by the fact that AdamAtomic released the sourcecode for the original. So the actual procedural level generation was copied almost one-on-one to 6510 assembly. As stated above the building generation depends on player speed, previous building height, and number of buildings since last special building. Adam actually explains this in quite some detail in one of his old blog-posts. Just look it up for more details!

Is there 1 book or resource you’d recommend for a starter in 6510 ASM?
Other people recommend the Jim Butterfield book, so I would try that one. But the most important thing is to just start with something. Begin simple and keep your motivation up by making lots of small things!

Why not the Spectrum?
Here in the Netherlands the spectrum was hardly around, so I don’t really have a link with the system. Also the capabilities of the platform don’t really trigger me to try to make something for this machine…

What was your fave c64 game back in the day?
Always a difficult question… I like my games fast and difficult, so Uridium is the one that comes to mind…

5 thoughts on “The Retro Asylum interview Paul Koller

  1. babyduckgames says:

    Great interview, nice answers to the questions also. Was encouraging that “Super Meat Boy” was one of the titles he would consider a c64 remake of, definitely one I would like to see.

  2. mrsid says:

    Amazing interview Steve. Paul sounds like a ‘normal guy’ who just loves programming for the C64. I love the fact that these new breed of developers are doing what they like without the silly deadlines and corporate red tape.

    Its a shame he wouldn’t do Chase HQ. Id love to see the version that the C64 was capable of instead of the pile of sh*t we got.

  3. scopie says:

    As for a new chase h.q? Why not just play turbo charge and quint your eyes a bit?

  4. Andy says:

    Great interview, really enjoyed hearing about the baking if the game

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