JR Life was made as a test to see what jrburger95 could do in the source engine and the end result was a simple GMOD clone. It's not as fancy as GMOD but it's free so if you don't want to buy GMOD you could try this if you want.
This is version 1.0 of JR Life which includes the sandbox game mode. This game requires that you have steam installed to play if you don't go to steampowered.com...