We all know that this one will have a massive modding community, many mods, and it will be easy to mod.

The Sims has flexible modding capabilites, an average size modding community, but the modding tools and SDK are not easy to manuever and use.

Easily, hands down, the most active modding community, most flexible modding capabilities, and easy to use modding SDK.

Fallout: New Vegas has a nice size modding community, easy to use modding tools and SDK, as well as flexible modding capablities.

This game has very flexible modding capabilites, a large and active modding community, and easy to use modding tools and SDK.

This game has flexible modding capabilites, a not so active and large community, but depsite that, it has an easy to use mod SDK.

This game has flexible modding capabilities, a large and active modding community, and has easy to use mod tools and easy to use mod SDK.

Despite it's massive modding community the modding capability is crap. Mods are unstable and a pain to install. Do not buy solely for the mods!

Half-life 2 brought the source engine into the spotlight. A huge modding community and the powerful Source SDK make this one game no one should pass up!

The game that started it all! Half-life runs on the GoldSRC which is a very flexible and powerful engine and is very mod friendly!