Star Wars: The Force Unleashed

If you have the Jedi Temple DLC you can kill bots in the padawan training room for lots of points. They are infinite until you destroy the statue-like things so just keep going until the achievement pops. The padawan training room is only about 10 minutes into the first level so you can start grinding right away (it's the big round room where all the training droids attack you, to the right behind the big door as you enter the great hall).

This is a good way to grind out force power achievements, too.

easiest on any difficulty on the final level. Near the end if you use a lot of force, you will get it, but otherwise after vader you should get it.