Hi The0r :P
This is a nice and simple game to play! I like the idea and simplicity of the gameplay. Outside of a game jam, a tutorial level would have been pretty good because I was confused for a little bit on what to do. Perhaps not spawning any zombies until the player mines 1 or 2 ores would have been enough as a mini-tutorial so the player could get a feel with the game. Also, maybe repeatedly pressing the down key to move the whole train would be better so it would have a more immediate feedback to the player instead of just holding down the down key to gradually move the train. I think this way, it wouldn't feel that "slow". Other than that, I think this quite a good game for a 2-day game jam. The art and gameplay feel great together. Moving the train to align the carts to the ores is quite fun as the main game mechanic and if you were to update and build on top of that, this game would be a fun game to play on-the-go on my phone. Very cool and great job! ;)