game engines

How do you go about designing a games engine, coz surely you need the game to test it. But you need the games engine to be able to make the game. Is it a viscious circle or am I confussing myself?

Also are there any good books around on designing game engines(preferably c++)

Cheers
Nick

...sort of.

The game is only a "user" of the engine.

Test the different calls you make to the engine (class or whatever it is).

What kind of game/engine is it?

Here's some game programming resource sites for c++

http://www.talula.demon.co.uk/allegro/
http://www.chesworth.com/pv/games/index.html
http://www.cprogramming.com/