"in a hot sweat". The article is needed. I agree with frightened and/or anxious.

Probably should be 'hot water," but who knows. It's a video game, it doesn't need to make sense.

Thank you!

I don't think he uses it to mean he is frightened. If he did, it's a malapropism because the expression that means that is to 'break out into a cold sweat.' But listening to the tone of his voice, he sounds pretty relaxed. I would interpret it more literally, either he is starting to sweat or he used it to mean he is in a sticky (difficult) situation.

Do you mean he is very frightened or anxious?