qmk_firmware

Othi's Universal HHKB keymap

Colemak layout. If you don't use Colemak then you'll need to also change the arrow key bindigns in other layers
Vim-like navigation layer so you can use vim binding arrowkeys in non-vim environment
Good modifier support so you don't have to hold 14 modifier keys at the same time
RGB indicating layer change(only work with plain colors so far, don't put your rgb to pulsing or any non static animation)

CL:

The base layer, default is Colemak
NM_MODE:

Vim-like arrowkeys in the home row, it's LHNE for JENK Colemak and HJKL for QWERTY

Also HOME, END and next/prev word (Ctrl + Left/Right) in 0, 4, w, b like in vim
VI_MODE:

The same as NM_MODE but with KC_LSFT held down for mostly highlighting
ACCENT + ACCENT_CAP:

Function row and Unicode characters

LHS:

Any Tap Dance key with the format of TD(XXX_NM) act as normal XXX modifier upon hold, but will hold and put you to NM_MODE when double click hold(a tap before the hold)(eg you can produce Alt + PgUp by pressing Alt + Alt + U)
KC_TAB acts as both KC_TAB on tap and KC_LGUI on hold
R3 CapsLock acts as both KC_BSPC on tap and KC_LCTL on hold
Holding KC_Q also puts you into NM_MODE
Holding KC_F puts you into VI_MODE for fast function keys

RHS:

3 keys KC_SCLN, KC_DOT and KC_SLSH in CL layer can also be held down for respectively KC_LCTL, KC_LSFT, KC_LALT for easier 2-hand modifier holding
Right modifiers hold the selected modifier with KC_LGUI at the same time, mainly for i3wm, you can change this to whatever combination you want

Unicode:

In case the keyboard output the 4-digit codepoint instead of the actual unicode, you need to change the rewrite input mode of the keyboard into the EEPROM(you only have to do this if the EEPROM was cleared or your current machine use another unicode compose method other than IBus/Linux's Ctrl + Shift + U). Change the corresponding Input void eeconfig_init_user(void). See this for availble input modes.
NOTE: make sure to keep your qmk env up to date with upstream