Hey! I'm glad you enjoyed our game, thanks for the kind words :)
We had more content that we couldn't add to this build, due to limited time, and additional powerups on train carts were part of it (we have a cool "rocket launcher wagon" 3D model waiting to be added to the game). I had the same idea about "choose your train composition" before the mission starts, so it's great to see other people would enjoy it, thanks! ^^