This is for Half-Life goldsource. It was developed with the young gamer in mind. I built it when my son was 12. He is listed as one of the beta testers.
There is not a lot of gun use in this mod. Mostly it is exploration through mario themed maps. The idea is to find different colored keys to open or find the same color door/exit. There is only one weapon in the whole mod, and that comes quite a way in. You will need to use the longjump module pretty often.
Young players really enjoy the mario sounds and mario-themed locations. The maps are small and easy to maneuver through.