SpaceSimCentral

"Nullpunkt" (or, in english: "Point Zero") is a short but polished 2D space game. It features a lot of action, modern graphics, an orchestral-electronic soundtrack, scripted sequences and voice acting.

It comes with a level editor (St2Editor.exe), although it is not targetted at beginners and originally wasn't designed for release at all. However, it is fully functional, just open one of the existing mission (.ini) files with it to see how it works. You can also modify 100% of the game content in order to modify Nullpunkt itsself or create custom space games using its engine.