Particle Systems Ltd. was a computer game developer based in Sheffield, England. The company was founded by Glyn Williams and Michael Powell. Games developed by Particle Systems include Independence War and its sequel Independence War 2: Edge of Chaos. The company was working on tactical combat game EXO, when it was acquired by Argonaut Games in January 2002[1] and became Argonaut's Sheffield studios. Argonaut Sheffield was closed in late October 2004 when Argonaut games was put into administration [2].