It has the added advantage that you can go back to a marine, and continue his actions later, if he has sufficient APs left. Taking on a greater daemon of Khorne Moving your marines around the map is a simple case of highlighting them and then pointing where you want them to go. You can also use a drag box to highlight more than one marine at once, though there seems to be a slight graphic glitch with the box, which occasionally becomes broken. Firing is a case of moving the mouse pointer over an enemy and clicking. Aimed takes double action points, but is more likely to hit.
Direct fire is used to target scenery rather than enemies.
Marines can also be set to overwatch, allowing them to snap-fire at enemies during the opposing force's turn. This is an important part of the way the game works and using up all your APs so you can't put up overwatch could cost you many squad members' lives. Psi power can be incredibly powerful, but it's not until your Psyker has been through a few missions that he's powerful enough to make good use of them. Powers available include basic attacks like assail and Hellfire, useful powers like teleporting the Psyker or friendly squads, destroying daemons or protecting the Psyker. There are some 22 in all, making for quite a lot of choice when you can only have a maximum four per Psyker.