The game was mostly about running as fast as possible the best levels where the ones you needed to do multiple things like outside with the pool.

you are able to ring the alarm anywhere on the level

This is pretty great!

Pretty cool idea! Music is nice too, I enjoyed it. You've got me on two levels where I wasn't actually supposed to trigger the alarm.

The art is a bit inconsistent. Most sprites are pixel art, but the floor isn't. Some of the images have outlines, some don't. I liked the rats all over the school :P

Also, I think there's a missed potential here. Most of the levels involve just moving from point A to B as fast as possible. It doesn't feel that much stealthy.

Overall pretty solid game. I gotta ask - why are the bathrooms on the outside of the school? :P