One of the main problems with making a "military" game into a movie is Hollywood's relationship with the Pentagon. Basically speaking, Hollywood producers want to save money on big-budget productions, so, the Pentagon allows free lease of military equipment such as rifles, uniforms, tactical clothing, and even gives greatly discounted rates for Jet and Chopper flying, as long as they get final script approval. This is all handled through the Pentagon's public relations department, and they ruthlessly refuse story elements that might paint the US armed forces in a bad light.
This was in reaction to films like "Full Metal Jacket" and "Dr. Strangelove," which used the Military's resources to tell stories that cast military culture in a negative light. Previously, military equipment was considered public property, and US citizens had access to it -within reason. Obviously you could not go and check out a tank at your local base, but if an American film producer could prove that it would be handled by professionals for use in a film and agreed to cover maintenance and other various costs, then the military could spare an old decommissioned tank, rifles, uniforms, and whatever else was needed for the film.
In an effort to curb the strong criticism of the military in the eighties, the military elected to absorb the majority of these costs with taxpayer funds, as long as they got a say in the final script. On case of the military rejecting a script: the comedy "Sgt. Bilko" starring Steve Martin was rejected, even though it just poked a light-hearted fun at the military. For the production, they had to turn to private collectors for their equipment and uniforms.