Mechanised Infantry squad.
We did half of character generation, with some slightly lower stats, and no regimental abilities.
They started as the bus to Basic Training pulled into the warehouse staging area. I gently described the area as they pulled up, then put on my best R. Lee Ermy impression and started yelling at them to move their filthy carcasses.
Since then, they've dealt with a Mutant Slave uprising on a frontier world, a band of those same mutants discovering an ancient (and previously undiscovered) Eldar outpost, and the reactivation of a Webway Portal to a Necron Tomb World. (They blew the portal up with an inordinate amount of explosives).
On their way to the next world, they had 'fun' with inter-regimental politics, rivalries, sporting events, and pranks, narrowly avoiding being caught and executed for Tech-Heresy, Biological Warfare, and Theft of a Commissar's Hat. (Turns out tipping a large barrel of raw sewage into the air filters of another regiment's ship-barracks is frowned upon)
They are currently on one of three worlds being assaulted as the opening Salvo of an Imperial Crusade into a sub-sector being reclaimed after the defeat of an Ork Waaagh. After surviving "Absolutely NOT D-Day in a Chimera", they are currently en-route to clear out a market town, and capture a bridge over a small river.
So after having fun in open terrain, mountains/forests, and the inside of a starship, they now get all the fun of urban combat.