Currently it only has three unit types, no complex moves like overwatch, and only one map, but it will grow. It's already fully playable and closely matches XCOM conventions. Left click on your (blue) units to select, click on empty space to move or on enemy to fire. Right click to deselect. Each unit has two action points (hence the game's name), shown as "horns". And some Hit Points, shown as the "beard". Units, naturally, die when out of HP, but can replenish HPs with "*" pickups. When next to cover (black or dashed squares), unit is protected by it on respective side and can "peek" out of it to shoot or, sadly, be shot at, just like in XCOM. Black squares are high cover, granting 40% defence and blocking vision. Dashed squares are low cover, giving only 20$ defence and no LOS obsruction.
When you hover the mouse over the square, you can see what is visible from it, and which enemies are flanked from (i.e. have no cover, marked green), or flanking this square, or both.
You can play against AI, it's a default mode. AI is quite competent, seeking cover and trying to flank you when possible. Also you can switch to 2 player mode, or even AI vs AI. Difference, basically, is that when you press "End turn", AI will make moves, depending on mode, for none, one or both sides if they have APs remained.
Even more, you can play on your own map! Just switch to Edit mode, and edit text field. # is high cover, + is low cover, G, A, S are blue units and g, a, s are red units. Note that map borders should always be high cover. Don't forget to press "Apply" when you done.