For the LD4 in 2004, we did a series of preparation compos. They were much shorter as a real LD, and as theme had the remake of an agreed upon classic game. One of them was Robotron (the others were Sapce Invaders, Frogger and Spy Hunter). In the Robotron one you had 4.8 hours for the game. My entry turned out to be a much better game than the one I actually wrote with 10 times as much time for the real LD. Oh well.
The game is rather simple. One directional input (cursor keys) controls the movement of the pink blob, another one (ASDW) controls the gun. Just like in the original.
There’s 30 partially random levels, and quite a lot of different enemies with unique behaviors.
Some of them, like the crab and the spider, were added in a post-compo version. Those are really hard (but fun, this is one of the few of my games I play through occasionally), as is the final boss. The crabs circle you, and the spider tries to aim ahead when shooting – back then I was still good at calculus, apparently The final boss doesn’t shoot you directly, but takes a lot of hits and spawns random enemies.