It was fun to play this game once. I don't think it grabbed me enough to win. The locomotive and the wagons crash into the aliens very easily, and I can't prevent it. The projectiles often miss. I think this is why I lost control of the game and lost. It's frustrating.
The maneuvering field is very small. Aliens can spawn right on the player.
Some hit sounds, and maybe gunfire or maneuvering sounds, would be nice. I don't know about other players, but I prefer background music, and here it's louder than the explosions.
You can add upgrades between levels.