Star Wars: The Force Unleashed

TheGearGuardian's solution helped me get this, I just thought I would add in some information to speed up the process:

Raxus Prime is the second level in the game, and has 7 Jawas very close to the beginning. You can skip most of the first section by taking some light damage and jumping towards the platform in the distance in front of you, after you Force Lightning the first object. The second object is right there at the end of this platforming section, so Lightning that too. Once you've blown a hole in the structure, go through it.

The game automatically saves here, but for whatever reason you can't get this achievement by reloading checkpoints. There will be 3 Jawas right there, and 4 a little further ahead. Kill all of them, pause, and save the game. Now go to mission select and choose this level again.

Doing that will save your kill progress, which is the only workaround to not being able to load checkpoints. You will have to wait for the loading and play through the first section 4 times, but this achievement should take no more than 10-15 minutes with this method.

Jawas are the short, weak robed enemies. You will first find them on Raxus Prime. Ugnaughts are the pig midgets you first com across in the bar at cloud city. Simply kill 25 of the two (mixed) for the achievement.

Both are very very weak and die in a hit or 2 with your light-saber. Any force attack kills them very quickly too.