I worked on a game about 18 years ago that used the mouse in that way - it was utterly f'(*&ng awful. The problem with using mouse forward in this way is there is no point of reference to return to when you want to reverse the process (slow down). Its not like a joystick where you can centre it and you are back to zero. It was all round the worst ever video game and just thinking about it has made me ill. I thought I had managed to blot it from my mind.

My game currently sports four different ways to move. My game in 3rd person, so some of these might not work if you're going with first person.

1) Mouse type movement, where mouse velocity is actually used to move without any buttons. This is pretty cool. The amount of mouse-movement needed is very small. There's also very little penalty for moving it too fast by accident, because the character changes speeds slowly over time. I think I just love the fact that no buttons are needed. The bad side is that you have to pick the mouse up and drop it if you keep walking really far in one direction. Which I do constantly just using Windows GUI anyway, so I doubt it's that big of a deal. This would work extremely well for tracking ball type devices.

2) Analog stick. It doesn't get any better than this, without legs.

2.5) WASD, arrow keys, and other such buttons, emulating the same result as an analog stick. Well, other than precise speed control, ..and precise direction control, and precise.. well, it's just not a very good emulation. My characters fumble around like idiots with D-Pad or button movement. I guess because I've built it from the ground up to rely on such precision. I still need to find more ways to allow more control without camera manipulation.

3) A method similar to point and click. You have an arrow that will circle your character, and can be pulled away from them or placed closer to decide speed, and it's direction is as precise as a stick. I'm still a little clumbsy operating it myself, in the midst of chaotic action.

4) Tank mode. Where you can turn left and right with keys and move forward or backward, like controlling a car. It allows precise direction control without the mouse, but I hate this setup. I added it just in case.

Thanks for the suggestions guys. Your input has confirmed to me that movement in this manner would be more of a hassle then something innovative and fun. Maybe I will stick with something more traditional.

as a closing note I'd like to point out that the WASD configuration evolved on the net out of many people trying different (and sometimes wild) configs on Quake deathmatches. I read it on a magazine, tried it and found it to be even better than my keypad config.

I mean, remember when you had to play with the arrows and the surrounding keys? yeech.
Most other controllers have slowly evolved too, so that makes coming up with a brand new scheme a bit hard. MS tried a new controller style, and failed somewhat. I forgot the name, but it was a weird two-piece articulated thingy for FPS games. You could actually play with it, so kudos anyways.

Actually, any "interesting" way of controlling a player would end up being a critical gameplay mechanism. For it to be different, it would have to deviate from our current waypoint or direct control mechanisms. One example would be "prodding" the avatar to head in a certain direction (or to do a certain thing), with ultimate executive power in the hands of the AI and determined according to character stats and disposition.

The automatic question, of course, is why anyone would want to play a game where you have to convince "yourself" to do something.

Just adding a note that there's a very cheap device you can buy that allows Playstation controllers to attach via USB on your PC. PS controllers are about the best you can own. You can throw it, stomp on it, burn it, cut it, microwave it, then still play highwire balancing games with the analog.

I own two of the PS2 controllers and have never played a FPS without it since.