How do you deal with the situation where you are invited to play a game, only to find it's wildly complex and takes 4 hours to finish, and you find yourself not wanting to play it within minute 5?

This has happened to me a few times. One I remember was the game Alchemist, where I just sat there confused as hell for 4 and a half hours while three guys were all talking about strategies. Tonight it was Terraforming Mars, where I was told it would be a 3 hour game, but by hour 4 we were halfway done. This time I said "it's 11pm, I have work in the morning, this will be my last hand" and the host got very passive aggressive with me. I just don't know what to do in these situations.

^Also is there a word for this? My girlfriend said I was "held game hostage" but I don't see that used in my searches.^

Update: I sent an apology for leaving early, and he wasn't too frustrated about it and understood my frustration which was nice. I told him I didn't think it was my cup of tea since it was so dense, but he kept trying to sell me on the game.

I just gotta learn how to decline with this guy, he is a bit of a "won't take no for an answer" person, but I'm still learning to be firm with boundaries.

I'm really a 45 minute or less person, and prefer games with like... 5 rules. I have communicated that before, but he really wants me to play the games he loves which I take as a compliment.

He did have me playing Dominion for a while, and that was a time when I just would suck it up and play for his sake since he was going through a divorce. We literally had the parks and rec sketch where I said "I don't really like Dominion" and he said "what do you mean? You've played all the games!"

He housed me when I was homeless, so it's hard for me to decline things with him since he showed me that huge kindness.