Oh yeah the drive is supposed to be mapped to the right trigger, we used a ps4 controller, so maybe that has a different button mapping.
The buttons can be changed in the Player Settings Dialogue box that comes up before you press "Start Game". The drive is listed as "Fire 1". The shoot is listed as "Fire 2" and the lock on button is "Fire 3" and the Hurt button (which allows you to absorb attacks for ammo when they get close to you) is listed as "Hurt".
We plan to update the page with the controls for both keyboard and gamepad shortly. So anyone can read.
I don't think the speed was mapped to the pressure applied but it's worth a shot. Hopefully it fixes the issue. If not, then maybe it'll work better with a keyboard and mouse, but you might still have to adjust the key mapping to have the most comfortable experience. Sorry for the inconvience.