Quick first post here; I've being in touch with Quake mostly by the Sega Dreamcast ports.
Seeing good non-fps Quake mods makes me wonder if anyone has attempted using the engine for a tennis game.
In most (if not all) tennis games, you control the player and the racket as an entity. For instance, you can't hit the ball to one side while running to the opposite. You have to get to one side and change your only directional control to wherever you want to hit.
Now, while this seems to make a more "tactical" game by positioning the player before hitting the ball, I rather see a game where you actually separate both aspects even if it reduces the challenge.
But then, without going into deeper aspects of tennis, a first person view would certainly make things more interesting.
Besides a keyboard/mouse configuration to control the player and racket respectively, having a sight could very well fit one of the principles of tennis: precision comes from on-center hits.
So, as a simplified concept, you could move the player with a typical WASD configuration, control the player view with the mouse, while having a sight that has to be aiming at the ball before hitting it. The longer you keep your aim at the ball, the more precise your shoot will be. Sort of an "aim lock" before you actually move the mouse according to where you wanna return it.
And shooting could be driven Virtua Tennis style (>VT2 actually); say left mouse button for a top spin shot, right for slice effect and both for a drop shot. The longer you hold either, the more powerful/further it goes.
Of course tennis is a fast game and this could be hard to do (hell, even hard to play), but this is just an unfounded concept without much knowledge of how the engine works and how (if) it could be implemented.
I would love to see something like this though. Given a base like that, there could be many possibilities to be added, such as different "aiming" timing given the player's abilities; stamina (maybe not as a graphical measure, but related to precision); sprint ( I could dig this as a rechargeable bar); and who knows what else.
One can dream, right?
*Theoretically* this could help to inspire someone.... Or bore them to death. Either way, I just had to post it.
Greets.