Talking to GamesRadar in a recent interview, Saber's Dmitriy Grigorenko mentioned that the original Space Marine 2 pitch was to "make a perfect sequel", a sequel that is effectively "a 360 game with a story campaign, some PvP, and a horde mode to accompany it". We'd say the team was largely successful in that endeavor.
"We wanted to make a perfect sequel [to Space Marine] – that was in the original pitch,
The 'perfect sequel' implies it's the exact same game – a 360 game with a story campaign, some PvP, and a horde mode to accompany it. We wanted to make a classic experience."
Elsewhere in the interview, Saber's creative director Oliver Hollis-Leick reminisced about playing Gears of War at a friend's house back in the day, and how a recent visit led to them playing through Space Marine 2 instead. The Gears games certainly seemed to have influenced this Warhammer subseries quite a lot, and playing through SM2 with that same friend "was just this amazing flashback experience!", the developer said.