If there's a Space Marine 2 in the works I'd like it to be better polished this time around. Two key things to improve that game, a cover system and a block function.
Simple squad commands would be nice, too, rather than spending a majority of the game alone in dank corridors. The opening levels of the game were impressive and fun, trashing the Orks. It quickly became a dreary slog, though, trundling the samey corridors slowly whittling down Chaos Marines one at a time.