Will you at least get a portion of the sales on the game? If the game really will be one of the biggest releases next year, a 20k salary is likely nothing compared to residuals/bonuses that might accrue to you.
There's very likely going to be a profitability bonus, but at the most it's going to be half of my salary. Pretty good for a bonus,but it's not making up for the low salary over all.
If you have 2 years experience in programming, you should be looking elsewhere in the game industry. The first couple of years are rough, but after "paying your dues" for a couple years, you'll find you can jump into another game dev job without much difficulty. This is a bit more problematic if you're not willing to relocate, since UK is one of the lower-paying game dev markets. However 30k usd is far too low even for the UK for a fresh-out-of-college junior programmer.
