Those are actually quite strange rates for games. That kind of pricing is generally more for long, spoken narrative (corp videos, radio spots, etc.). Did you get that from "voices.com"? ...
For games, we usually hire either by the hour of recording, by the character or by the 'phrase' or some combination thereof.
For large games, go by the SAG rates, which specify things like the # of characters you can get for a 4-hour block, etc.
For smaller games, be prepared to be more flexible. Not necessarily on money, but on things like the # of characters, etc.
The SAG contract for games is largely predicated on the "AAA" model game, where you have major characters, plots, and many thousands (or tens of thousands) of lines of dialog, where a "line" is a complex character sentence. (eg "Ok..I've set up the accompanying troops to deploy to the east forward area..")
By contrast, most small games require far less, and are also less likely to have complex plots. But they may want more characters, etc. And the dialog is likely to be much simpler (eg "hey, great shot!" "you found the treasure", etc.). As such, things like the SAG 4 hour minimum dont' really make sense.