For sound generation/effects you should read some book on DSP...It's really exciting having your own sound engine based on synthesis...you have full control on the sound. It can be dinamically adapted to the situation of the game ecc.
If you want you can use stk: http://ccrma.stanford.edu/software/stk/
have a read at this classic book (free!): http://www.dspguide.com/pdfbook.htm
anyway making a game based on sound files (like many games do) is much more simpler...so think about it.