Rock is a space combat sim / mech sim / FPS hybrid that was in development in 1999 / 2000 by Singletrack for PC, but later cancelled because the studio was closed. The team planned to combine 3 genres into a single game, to let the player a lot of freedom in how to resolve the missions. It was an ambitious project, as we can read from a preview published in Computer Gaming World magazine (thanks to Roushimsx on the HG101 Forum):
Imagine a game where you can jump into a tarfighter, dogfight our way to a martian plain, hop out, toss a grenade in a Mech to kill the pilot so you can claim the assault robot for yourself, rampage across a warzone in your new weapons platform and finally jump out and enter a building, killing some fuards before you plat explosives to level it – all of this without any load screens to stall the action.
Cooperative online multiplayer was also planned. After Singletrack closed down, the Rock team ended up moving on to Incognito Entertainment (later purchased by Sony) and started to work on Warhawk for the PS3. You can feel that some of the concepts from Rock were implemented into Warhack.
Thanks to Robert Seddon for the contribution!