I have been trying to think of the name of a casual game in which you help or are helped by an archangel held in durance vile.

I will have to think about this for a bit. Do you remember anything else about the game?

There is a dungeon. The angel is behind a sealed door or wall in an alcove and I believe got there by losing a battle. I vaguely think we hand him tokens/coins/objects through a slot and we only see his face when he is ready to talk after getting the right item.

My hazy sense is that the developers are Eastern European. At any rate, I was reminded of this game when replaying the excellent 9: Dark Side.

The only thing that comes to mind as a possibility when I read your description is Enigmatis: The Mists of Ravenwood.

That's a surprise. Checking purchase history, I scrolled right past the Enigmatis series when looking for title that would jog my memory. Thanks.

That was definitely one of the better HOPAs I've played. And there was even a Monty Python reference in it.

That's it. I checked. Mists of Ravenwood is a good game. I'll replay soon.

I'd like to replay this one as well.

You two are GOOD! I was trying to remember what sounded so familiar about it. Excellent game and one of my faves, too. Maple Creek and Shadow of Karkhala aren't bad, either. Good length and complexity, although the HO scenes weren't much fun.