Looks like a few places have the manual, one can be found here.
There’s nothing hugely exciting in the manual, apart from interesting concepts for other consoles, like importing your own levels.
However, basic controls are as follows:
Arrow keys: Move/aim
Mouse: move camera
RMB: Bring up weapons menu
F1-F10: manually select weapon categories (instead of mouse)
1-5: set grenade detonate time
– and +: set grenade bounce
Spacebar: fire current weapon. For projectiles, hold down space for power
R: after firing, see a replay of the shot. Probably best to mash this as I’m not sure when the game expects the press
You can initiate Sudden Death mode in the escape menu – this sets all worms’ health to 1 to make the game end a touch quicker