Let's look at - Cortex Command
Multiplayer jump'n run shooter in 2D.
Left button – Shoot
Right button – Sharp Aim
Move mouse – Aim
A – Walk left
D – Walk right
K+W – Pick up weapon
Q – Change actor (Left)
E – Change actor (Right)
E+Q – Buy menu
ESC – Main menu
R – Restart
1 – Speed +
2 – Speed –
M – Change vision
Found a very detailed info here: