Grin began preproduction work on a Final Fantasy spin-off game, Fortress, in the second half of 2008 when Square Enix outsourced it to the Swedish developer.

[6] However, after six months of development, Square Enix reclaimed the project without paying Grin, due to concerns over the quality of the work.

[2][7] Grin co-founders Ulf and Bo Andersson claimed that "Square Enix had already made up its mind that Fortress wasn't a project it wanted anymore".

[8] Square Enix's withdrawal left the Swedish developer in financial difficulty and with no other ongoing game project.

Bertil Hörberg, who worked on both Bionic Commando and Bionic Commando Rearmed, went on to form Hörberg Productions, a one-man studio responsible for the well-received Gunman Clive (Nintendo 3DS, iOS, Android, Steam) and its sequel Gunman Clive 2 (3DS, Steam).

The first installment of the engine was developed in close collaboration with Nvidia, aimed to showcase the capabilities of their latest graphics chip at the time, the GeForce 3.