The game is inspired by the zombie survival horror genre. You start off with just one soldier, in a military base being overrun by the undead. Your missions are to find out what is going on, link up with your buddies and your CO, and retrieve valuable equipment, weapons and ammo before the zombies get you.
At this stage I'm still playing on the early levels, and have acquired one buddy. Unlike Space Hulk, where you begin with at least two fully-equipped squads of marines, here you're on your own until you find other survivors to add to your group. Also, much of the tension stems from the fact that you either have NO weapons, or are on limited ammo. Running out of bullets as a horde of zombies is coming down a corridor towards you is quite an evocative experience!
The other brilliant aspect of this game is the fact that you have hidden movement: the iPad is running the zombies, and it keeps thems hidden from you until your characters can see them. In Space Hulk, marines had scanners, so could track incoming Genestealers without perhaps knowing precise numbers. Here there is no such thing - you don't know zombies are there until you see them.
Also, if they can't see you, there is scope to simply sneak past them. This element of fog of war is something lacking in boardgames, but can really be brought to life on the iPad. There are big possibilities here for wargaming on the iPad if the right developers can get on board with the right apps.
As I've said, I have only played a few levels of the game so far, but it is tense stuff. I've been hellishly busy this week, so my iPad has lain sadly neglected, despit the foul weather over last weekend! I have not been able to find out if there is a two player variant for TacSol - if there is scope for another player to control the zombies, or even to play the game online via the Apple Game Centre (which has obliging downloaded itself), that would be fantastic.