Payment for my work [on hold]

Recently, I was working with a Swedish guy on an indie pixel rpg game (don't bother pointing out that a million of them already exist, i know). We got in contact via a programming site's post a job section, and at the time I started the project, since I wasn't too keen to money, we decided to negotiate that later (he was willing to pay, but i foolishly declined). I worked with him for 6 months, and the game is very nearly in it's alpha stage. Seeing as how the game was so nearly finished, he talked to some guys (in Sweden, the govt apparently has a free consulting service for small business owners), and now he's asking me for the source code. That isn't such a big issue by itself, but apprently he thinks he owns the game 100%. He has been paying the artists and stuff so the assets are owned by him, but definitely not the code - which he apparently assumes he owns. I talked to him yesterdy regarding the same, and he's (after a lot of talking) willing to give me 20% ownership of the game, an upfront payment of 400$ and 20% profit sharing. However, on earlier ocassions, he has already mentioned upto 50% profit sharing, and i'm not sure if 20% ownership and 400$ payment is enough to compensate me for my efforts.

So I'd like to ask you, what do you think about this? Is his offer fair, and should i take it? Or should I ask him to consider some other terms? Failing that, should i leave the project?

I'm sorry for the broad question, but i'm just 18yo and this is (was supposed to be) my first commercial project, but now i'm just plain confused.

P.S. sorry if this is the wrong forum, but i really couldn't think of a better one.