The game is turn-based so you and the enemy (AI) take it in turns to move your players and perform actions. The general order of play is as follows:
You control the slayers on the map. Your job will depend on what the level requires of you but in all cases your ultimate job will be to keep them all alive!
Your slayers have to be moved one at a time. You cannot move a slayer in the same turn if that slayer has already been moved even if that slayer has unspent actions left.
If you deselect a slayer and select another slayer by accident but don't move the recently selected slayer you will be able to reselect the original slayer and continue using actions.
On some levels you might encounter doors. You can open and close these only when in an adjacent tile and facing the door. You also have an option to shoot at a closed door, if you hit it the door will be destroyed and can no longer be used and will always be 'open'.
Doors can be crucial in some strategies and so think about whether you want to leave a door open once through it or whether you want to just blast it off its hinges.
To attack a door or vampire you must have a slayer selected, then tap on the target. If you are able to shoot at the target it will show a targetting marker otherwise hints will be shown on the screen to indicate why you cannot shoot at the target. Once targetted, tap again on the target to shoot at it.
There is a chance shots miss but if you continue to shoot at the same target without moving or performing another action the likliehood of hitting the target increases with each shot.
You can only shoot if you have enough actions left but with a target selected you can move and the shot will be fired too without any additional cost however you will not receive an aim bonus like you would if you don't move when you shoot.
Line of sight is important when keeping an eye on approaching vampires (see Hints and Tips). Each slayer can see directly in front of him and to the sides so long as nothing is in the way. The cannot see anything behind him. For example, if he is facing down a 'T' junction, he will be able to see down all directions, however if he turns to face right, he can only see down the East section and South section of the 'T'.
A fire arc is the area with which you can fire upon a target. Every slayer has the same arc and this projects at 45 degrees each side of where he is facing, i.e. diagonally away from him to his left and to his right. Targets (vampires, doors etc) outside this arc cannot be fired at. The exception is with the demolition slayer, his bombs have a large area of effect so as long as he can target a square near a target, he might still have a chance of hitting a target.
There are three difficulty levels ranging from easy to hard. Easy still won't be a walk in the park, well not unless that park is full of bad things wanting to suck your blood. However the levels attempt to swing the chances of success toward you or the vampires. Regardless of the difficulty setting, you will still need to apply skill and hope for a big dose of luck too.
Successful hit chances are improved, especially when in melee with a vampire. Vampires act more predictably, allowing an amount of herding.
This is the classic balanced setting, how the game should be played.
Enemy re-inforcements are increased by 1 per turn. There is also a chance that alert slayers firing upon a moving vampire during the enemy turn might break their crossbow taking them off alert status while they fix their weapon.
These are more likely to get you killed sooner than actually help.
Can't figure out why things are happening, missed the tutorial levels? This should help a little bit.
Find out what it looks like. Viewer beware - these are developer graphics!