my second game, naalaa invader

[aliensoldier]

I probably won't be able to look at the game until Saturday or Sunday, because I'll most likely be travelling. But I'll do my best to track down the runtime error then

You have looked at the code and found the error, I think it could be the indexof() function, it is a function of yours and I don't know how it works exactly, although it could be something else.