I tried to go down a tunnel that the surrounding area had been destroyed, but the stairs still existed, but every time I tried I couldn't. What was worse was that everytime I tried it responded as if I was attacking it! I lost multiple APs every time I tried to enter it, until I had none left. Steve could you explain what happened there?
What most likely happened was that there was another unit at the other end of the stairs, and so close-combat ensued. Unfortunately I wouldn't be surprised if the game didn't show the other unit after the attack (he would have presumably been hidden by LOS before the attack); I can't remember if I added that "feature".
Its likely that the exit to the tunnel i.e. the other end, either had someone on it, or it was destroyed by grenade so it effectively had no working exit.
Cheers for the reply, thought that might be the case, but not sure why you have to lose APs trying to do so. If you walk into a wall you lose none. If there is no exit then you should just not move. Or if someone is blocking it the other side then no movement. If you lose APs because you are engaging in combat then the bloke at the other end should take damage as should you.