Freeform

Freeform is basically roleplaying without the rollplaying. It can operate with or without a GM, but if your GM is a dick then rocks fall, everyone dies. Freeform roleplay might have rules, but they're probably really simple and vague, like FUDGE. There probably won't be any classes, levels, experience points, or any of the other crunchy stuff that powergamers like.

If your GM wants to use this style it is because he is likely too lazy to do any real prep work.