CPC platform support is mostly limited to what the firmware supplies.
As a result, there's no sprite libraries, sound support or anything else that might make writing games easier. On the otherhand you do get native floating point support (again using the firmware)
As a result, you'll need to look to third party libraries unless you want to write all the routines yourself. cpcrslib (http://code.google.com/p/cpcrslib/) looks like it provides sprite support and integrate them in.
We will, of course, gratefully accept code donations which improve the quality of the CPC support.