Star Machine, the FPS mode of Star Citizen, was promised in April but has been delayed indefinitely while Cloud Imperium Games sorts out some issues.
Unfortunately, the current state of Star Marine isn't up to the standards that the studio and publisher hoped for - but has abandoned legacy code in favor of the "Generic Instance Manager" (GIM). Less than 20 percent of the overall Star Citizen development team is working on Star Marine, and it's unknown when it'll be completed.
"There are several issues that will need additional time in order to deliver the first iteration of the gameplay we want you to experience," said Star Citizen boss Chris Roberts in a recent "Letter from the Chairman" blog post. "The challenges facing the FPS launch are a mix of technical blockers and gameplay issues. The most significant technical hurdle faced today is the networking backend."