I've created two rom hacks of the orginal Donkey Kong game: Donkey Kong - Freerun Edition and Donkey Kong - Crazy Barrels Edition.
I consider these two Editions exercises in understanding the game code of Donkey Kong and the possibilities of changing the logic of the game. In the near future I will also try to go a step further and try to change the layout of the screens (e.g. add gaps in girders, change position of ladders, etc) and to introduce new elements in the screens (hammers in elevator screen, springs in rivets screen, etc). I know these kind of alterations are done before, but I like to learn by doing it myself. My ultimate goal is to create an entirely new game like Donkey Kong II or Donkey Kong Remix. I already have some ideas, but do not know if they are feasible.
Donkey Kong Freerun Edition:
https://github.com/PaulGoes/DK-Freerun-Edition/raw/master/dkong.zipIn the Freerun Edition you can play the complete game without enemies. So there are no barrels, no fireballs/firefoxes, no pies and no springs. You are free to roam the level screens for as long as the bonus timer allows. But beware: you still die when you fall off a girder, fall through a rivet hole, jump in a burning oil can or miscalculate a jump to an elevator. The faster you run through a level the more points earned based on the time remaining on the bonus timer. Points are also be earned by picking up the bonus items just like in the original game.
I'm a lousy Donkey Kong player and will probably never be able to experience the famous kill screen myself playing the original game. But this Freerun Edition made me do it: I reached the kill screen ... after more than an hour of pointless running and climbing. But then something interesting happened. Because there are no enemies you can speed through the barrel screen and actually make it to the top in the short amount of time that is given. So I could also run the conveyor screen on level 22! However, on the next barrel screen I was to slow and got the kill just before reaching Pauline. A clip with this is included in the YouTube video.
Donkey Kong Crazy Barrels Edition:
https://github.com/PaulGoes/DK-CrazyBarrels-Edition/raw/master/dkong.zipIn this Crazy Barrels Edition you play the barrels screen over and over again. But the internal difficulty starts where the original stops: at level 5. In this game this is called the Agitation Level of Donkey Kong, displayed on the screen as A=5. When a barrel screen is cleared, the Agitation Level goes up for the next screen. But this is not the only change. Donkey Kong throws a lot more crazy barrels than the original game. Just like the original game, the first barrel is always a crazy barrel that ignites the oil can and spawns a fireball. In the original game the second barrel is never a crazy barrel, but in this game it might be. The game is hard and Donkey Kong shows that by yelling 'You won't get that high!'. But he has a little remorse and gives you 6 lives instead of 3.
A little background. In 1981 (what was so special about that year? besides that I was 12 years old!) I started programming Basic programs for the TRS-80 micro computer. I quickly hit some limitations and started programming parts in Z80 assembly code. One year ago my interest in the Donkey Kong arcade game was set after watching the 'King of Kong' documentary. A few weeks ago I discovered the Donkey Kong II and Donkey Kong Remix versions which made me wonder how difficult it would be to do something like that myself considering my experience in Z80 assembly programming. After some Googling I found the disassembled DK code (by Kef Schecter on GitHub) that was augmented with lots of very helpful comments. I couldn't resist to start changing little bits (or actually bytes) using a simple hex-editor to see the effects. And that led to the ideas for these two rom hacks.
