Graal Online, p2p but you can play as a trial account forever. Trials aren't that limited except that you go in observer mode every hour for a minute, than you can keep playing again.
The editor is great, they have their own scripting language so you can dim a map, or make lamps, cars, weapons. Anything.
Here's a screenshot of the latest level I made before I stopped playing, and a screenshot of the editor, with the script window open. I've dimmed the level, but it doesn't show on the screenshot
