Default Controls

Arrow Keys - Move
Z - Confirm, Speed up battles (Hold)
X - Cancel, Open Menu
Q/W - Change pages in the Skill, Status, and Equip menus.

F1 - Options Menu
Launch in Fullscreen - This is a built-in Fullscreen option for the game's engine. It is recommended that you don't use this and press F5 to bring the window into fullscreen instead.
Gamepad/Keyboard - Use these tabs to rebind keys. In this menu, Confirm is treated as C, Cancel is treated as B and Change Pages are treated as L and R.

F5 - Toggle Fullscreen
F6 - Toggle game resolution. (2x and 3x)
F7 - Alternative Fullscreen mode that changes the whole screen's resolution. Sharper image, but not recommended for streaming or video capture.
F8 - Half resolution (320x240)
F12 - Reset Game

About the F12 Function (STEAM ONLY)

Due to an engine limitation, the F12 key is used to reset the game and is not used to take screenshots through Steam. If you want to take screenshots of the game, you can do so externally, such as using the Print Screen Key or using Windows' Snipping Tool.