There is an awsome game called Garry's mod, it is a source modification or better said you need a source engine to run the game. The more source games you have(Half Life 2, Counter Strike Source, Day of Defeat...)than you have more party for the game. And you can do everything you want, build you house, catapult, flying bathtub, flying ragdolls... You can buy it from Steam for 10$ or just download the stalone version. Caution you need a source engine game. But if someone has the game, I have a problem. Cuz it is downloaded, when I start it from Steam to play multiplayer and when I wana join a server it sais that my version does not match the server version. But I and the server are version 10, so if someone can help thanks.