That game needs simple and effective expansions that would not drastically change the game system.  Both existing expansions were small, but packed a lot of punch. 
Quite simply, I would like to see Mission pack 2 and space marine pack 2... 2 new teams, new terrains with activation abilities, new location for more variety, more event cards and a new enemy type that is spawned like the brood lords or adrenal genestealers (maybe chaos space marines that would also have an attack range).

As Dam said, this game is not a walk in the park!  I guess the difficulty level is part of its appeal.
 
I usually spend the first couple of turns building up support and moving marines to build a cohesive defensive formation.  Leaving a marine without support at the mercy of a swarm may pay off one or two times if you are lucky, but it unfortunately won't get you far very often...
 
Good luck to you

That game needs simple and effective expansions that would not drastically change the game system.  Both existing expansions were small, but packed a lot of punch. 
Quite simply, I would like to see Mission pack 2 and space marine pack 2... 2 new teams, new terrains with activation abilities, new location for more variety, more event cards and a new enemy type that is spawned like the brood lords or adrenal genestealers (maybe chaos space marines that would also have an attack range).