The game plays well, reminds me of pistol period in Ja1.
Is it possible to turn on showing remaining APs at the end of moving? Or am I missing something?

It still has much less basic features than even Ja1 (no grenades, no destructible environment, no suppression etc.), but definitely playable and enjoyable.

The interrupt thing is still not clear for me. Why sometimes it is shown and sometimes not, even if I have enough APs? Why the interrupt cone disappears when the merc crouches?

Indication above enemies is hard to see, especially small text and when zoomed out.
No fullscreen mode.
Is there a hearing model in the game or enemy can only be detected by sight?