Is it possible to decompile a PS2 game, and view usable code?

[ThereCanBeOnlyOne]

I'm trying to strip SpongeBob: Battle for Bikini Bottom down to it's bare code to see how certain game play mechanics work in-depth as I'm trying to make a game myself, and want to see how they accomplish certain things. The problem being is that the PS2 version (and GC version (ripping the game now from my Wii)) use this weird .hip/.hop file scheme (https://i.imgur.com/C7rbWD0.png), and aside from a single .ini file (http://pastebin.com/adPYZ3wP) that contains some variables that I presume are for debugging, and some dev. commentary too there is nothing usable. 

I found that the .hip file appears to openable with an extraordinarily pricey program called Houdini. I tried to open it with, but it didn't work. Any ideas? I'm at a loss here. Probably just a pipe dream, but maybe someone here knows better.

[dogen]

I don't think you can do this(maybe sort of with the debugger? but even then I think it would be difficult to know what you're looking at), but even if you could can you read mips assembly code?

[FlatOut]

Just stick to reading the code of games that are open source.