These are StepMania's basic default keybindings used to navigate the game. They can be changed in the Config Key/Joy Mappings screen in the main options menu.

key	action
Enter	Go forward through a menu or screen
Escape	Return to a previous screen
←, ↓, ↑, →	Navigate the menus (and press arrows during gameplay)

Combination	Function
Alt + Enter	Switches between windowed and fullscreen.
Tab	Speeds up UI to 4x while held, including animations and selections.
`	Slows down UI to 0.25x while held, including animations and selections
Scroll Lock	Jump immediately to the main options menu. You can change this key binding in settings.

Combination	Function
Screenshot key (PrintScreen or F13 by default)	Save a lossy screenshot. You can change this key binding in settings.
Shift + Screenshot key	Save a lossless screenshot.

Combination	Function
F1	insert coin
F2	reload metrics.ini and language files, reload all textures, refresh NoteSkins, refresh CodeDetector cache
Shift + F2	reload metrics.ini and language files, refresh NoteSkins, refresh CodeDetector cache
Ctrl + Shift + F2	reload metrics.ini and language files, reload overlay screens
Ctrl + F2	reload _fallback theme's Scripts directory, then current theme's Scripts directory
holding F3	open the Debug Menu

The Debug Menu is accessed by holding F3. From there, you can toggle between its three modes:

Combination	Mode
F3 + F5	Main Debug Menu
F3 + F6	Theme Debug Menu
F3 + F7	Profile Debug Menu

These keyboard shortcuts are available when the Debug Menu is in Main Debug Menu mode.

Combination	Function
F3 + 1	Toggle between Home mode, Freeplay, and Coin mode
F3 + 2	Toggle slow animations
F3 + 3	Halt rendering
F3 + 4	Toggle Lights Debug, used to test arcade cabinet lighting
F3 + 5	Toggle Monkey Input, used by themers for stress-testing input handling
F3 + 6	Toggle Visual Rendering Stats (FPS, average FPS, and vertices per frame counts)
F3 + 7	Toggle Vsync
F3 + 8	Toggle Multitexture (?)
F3 + 0	Write Preferences.ini to disk
F3 + E	Pull back camera; useful for themers when designing screens
F3 + R	Decrease StepMania volume by 10%
F3 + T	Increase StepMania volume by 10%
F3 + A	Mute all "Actions" (typically theme sound effects)

Combination	Function
Control + Shift + R	Reload the currently selected song and regenerate the cache for it
Control + any alphabet key	Switch the MusicWheel to Title sort and jump to the letter you pressed. e.g., Control + M will sort songs alphabetically and place you at the start of the M group.
Control + Backspace	Permanently delete the selected song (if AllowSongDeletion is enabled).
F9	Toggle between transliterated and original song titles.

The following was taken from https://github.com/stepmania/stepmania/blob/master/Themes/_fallback/Scripts/03%20Gameplay.lua#L272

"+" means held at the same time. "," means one after the other. If a setting has more than one combination it will be listed on another line.

Default combination	metrics setting	What it does
Left	PreviousSongButton	Previous song
Right	NextSongButton	Next Song
Start	(hardcoded)	Begin Song
Left+Right+Select	(hardcoded)	Opens sort prompt
Left,Left,Right,Right	(hardcoded)	Exit
Start, Start OR Holding Start	(hardcoded)	Open Options Screen
Select	(hardcoded)	Open Options List
(Not used)	PreviousDifficultyButton	Switches to the previous difficulty. By default, CodeDetector is used instead.
(not used)	NextDifficultyButton	Switches to the next difficulty. By default, CodeDetector is used instead.
Ctrl+any letter	(hardcoded)	Switches the sorting to alphabetical and then jumps to the letter you've pressed.

Start, Start or Holding Start opens the options screen if metric "OptionsMenuAvailable" is true.

Select opens options list if metric "UseOptionsList" is true. (Using the select button to open the options list is hardcoded and can't be changed, but you can add an additional combo to open the OptionsList using CodeDetector.)

Default combination	CodeDetector setting	What it does
Left+Right OR MenuLeft-MenuRight	NextSort1 NextSort2 NextSort3 NextSort4	Cycle between sorting modes (in some themes)
MenuUp, MenuRight, MenuRight	NextGroup	Jump to next folder
(no default)	PrevGroup	Jump to previous folder
Up, Down, Up, Down OR MenuUp, MenuDown, MenuUp, MenuDown	ModeMenu1 ModeMenu2	Open up the sorting selection menu (in some themes)
MenuUp-MenuDown	CloseCurrentFolder	Close the current folder

Use Up, Up, MenuUp, MenuUp, Down, Down or MenuDown, MenuDown for change difficulty.

Some themes use Left+Right for Sort menu instead of Cycle between sorting modes, leaving this function disabled.

Some of these are for Pump mode, which is where the UpLeft, UpRight, DownLeft, DownRight buttons come from. They don't affect Dance mode, so you can ignore them if you don't play Pump mode.

Default combination	CodeDetector setting	What it does
Left, Right, Left, Right, Left, Right, Left, Right	CancelAll	Remove all modifiers
DownRight, DownLeft, UpRight, UpLeft, DownRight, DownLeft, UpRight, UpLeft, Center	CodeDetector setting	Enables/Disables the Mirror modifier.
(no default combo)	Left	Enables/Disables the Left modifer.
(no default combo)	Right	Enables/Disables the Right modifier.
UpLeft, UpRight, UpLeft, UpRight, DownLeft, DownRight, DownLeft, DownRight, Center	Shuffle	Enables/Disables the Shuffle modifier.
UpLeft, UpRight, DownLeft, DownRight, UpLeft, UpRight, DownLeft, DownRight, Center	SuperShuffle	Enables/Disables the SuperShuffle modifier.
(no default combo)	NextTransform	Cycles between transform modifiers
UpLeft, UpRight, UpLeft, UpRight, Center	NextScrollSpeed	Jumps to the next scroll speed (ex: 1x -> 2x, 2x -> 3x)
UpRight, UpLeft, UpRight, UpLeft, Center	PreviousScrollSpeed	Jumps to the previous scroll speed
(no default combo)	NextAccel	Cycles between Accel modifiers
(no default combo)	NextEffect	Cycles between Effect modifiers
(no default combo)	NextAppearance	Cycles between Appearnace modifiers
(no default combo)	NextTurn	Cycles between Turn modifiers
UpLeft, DownLeft, UpRight, DownRight, UpLeft, DownLeft, UpRight, DownRight, DownRight	Reverse	Enables/Disables the Reverse modifier
(no default combo)	HoldNotes	You know what this does.
(no default combo)	Mines	You know what this does.
(no default combo)	Dark	You know what this does.
(no default combo)	Hidden	You know what this does.
(no default combo)	RandomVanish	You know what this does.
(no default combo)	NextTheme (DEPRECIATED)	Cycles to the next theme.
(no default combo)	NextTheme2 (DEPRECIATED)	Cycles to the next theme.
(no default combo)	NextAnnouncer (DEPRECIATED)	Cycles to the next announcer.
(no default combo)	NextAnnouncer2 (DEPRECIATED)	Cycles to the next announcer.
(no default combo)	BackInEventMode	???
(no default combo)	PrevOptionsList	Goes to the previous options list menu, if UseOptionsList is enabled on the music select screen metrics.
(no default combo)	NextOptionsList	Goes to the next options list menu, if UseOptionsList is enabled on the music select screen metrics.

Default combination	CodeDetector setting	What it does
MenuLeft-MenuRight OR Select	SaveScreenshot1 SaveScreenshot2	Save a screenshot.