Deca is the SI prefix for 10, much like kilo is for 1000 and milli for 1/1000. Wikipedia knows best. =P
The drug you're thinking of probably contains ten of something in its chemical formula or whatever, and thus has a long and complicated name that starts with deca.
The game itself looks rather nice. Wii Sports with more depth and content, which is pretty much what I hoped my bundled title would've been like.







