As a default, the controls are below:

Name Default key
Forward W
Backward S
Walk left A
Walk Right D
Jump Space Bar
Shoot/Slash Left Mouse Button/Left Ctrl
Hang on wall, (only while on air facing wall, using melee weapon) Right Mouse Button
Reload R
Melee Weapon 1
Ranged Weapon #1 2
Second Ranged #2123 3
Item #1 4
Item #2 5
Previous Weapon Q/Mouse Wheel Up
Next Weapon E/Mouse Wheel Down
Main Menu Esc
Game Status Tab

These can all be mapped to different keys through the Options menu.