For a full visual walkthrough of the campaign missions and boss fights, watch these longplays:
If your game is crashing, check the Crash & Performance Guide for compatibility settings and multi-core CPU fixes. Warhammer-40000-Space-Marine.rar
You do not have regenerating health. You must Stun enemies (typically with 'F' or Circle/B) and perform an Execution to heal. For a full visual walkthrough of the campaign
A detailed Steam Community Guide covers every collectible (Servo-Skulls) and mission objective. Warhammer-40000-Space-Marine.rar