hi, I wanted to do a classic space invaders game with BGE. how is it possible using the logic bricks to have a sprites row moving back and forth for a certain number of times and then moving down of a row?
This has nothing to do with sprites.
You need to describe the motion. There are a lot of options to do that.
You can create an animation from begin to the end.
You can create multiple animations and combine them (e.g. a forward motion, a down motion).