Gearbox Software essentially rebuilt Aliens: Colonial Marines in just nine months, explaining why the final product doesn't compare to the earlier demo version, a source has told Kotaku.

The impressive demo - shown to press at trade shows and press events - was created by TimeGame with some animation work done by Gearbox. A source says the demo was running in real-time, but a top end PC more advanced that the average Joe owned was required.

"We were told many times through demo production, 'Don't worry about performance, just make it awesome,'" said one source. "There was a reason [the demos] were never playable."

The problems began once this high quality demo had to be optimised by TimeGate for consumer PCs.

"We were constantly cutting back more and more in terms of texture, shader and particle fidelity, in order to fit into the jacked memory restraints," explained another source.

It wasn't until last summer that Gearbox took over development, but was faced with the task of changing pretty much everything - TimeGate's game didn't even run on PS3.

A source familiar with later builds of the game said: "[Gearbox made] big changes to lighting, texture and shader complexity... Design elements were altered or redone entirely. It looks like a lot of [TimeGate's] assets remained intact, with the exception of lower-res textures and faster-performing shaders."

A source at Gearbox confirmed rumours that the game which arrived in stores was a rushed effort, with the studio unable to extend its deadline with SEGA even though it knew the game was a mess.

"The game feels like it was made in nine months," said a source who worked on the project. "That's because it was."

Source: Kotaku