Augmentarium

It is playable on lowest settings.

Instructions to set 640x400 resolution:

Download BulletstormINIeditor

Use BulletstormINIeditor application to open StormEngine.ini in My Documents\My Games\BulletStorm\StormGame\Config

Edit next:

[SystemSettings]

ResX=640
ResY=400

[Engine.Engine]

bUseBackgroundLevelStreaming=False

Loads level in beginning and not in background during gameplay

Save & Exit
Play game!
11+ FPS