/dungeon /dungeons - list any dungeon instances (including their id, time left) you are bound to. clicking on a specific dungeon allows you to extend an instance for 12 hours (max 24).
/gc - ?
/grid - debug skill/detection ranges (will lag/disconnect you if you leave it on for too long)
/help /commands [skills|stats|equip] - show help tutorial for a specific ui
/info [hide|set] - hide/show all background textures on the map, except for foreground textures and entities.
/invite [playername] - invite a player to your group
/join [channelname] - join a chat channel
/leave - leave your current group
/leave [channelname] - leave a chat channel
/movement - enable movement debugging?
/notify - play sounds on incoming messages [default: disabled]
/packetlog - print packetlog to chat
/pe - shows the character effect state (idk what this means)
/platforms - currently broken, as you can't hit enter once you type this exact command
/quit! - force quit the game
/refresh - ?
/report /feedback /support - open the ticket UI window to write about an in-game issue/bug/support
/report [player] - report a player
/reset
/respawn - ?
/return - leave a map, usually for custom maps
/roll - roll a number from 1-100
/servertime - echo the server time (UTC)
/sn - play a bell sound (idk what this does, probably to test notify)
/sounds - debug sound tab, check all sounds currently playing in the map, effect (NPC?) positions
/status - basic version for normal players. display map name
/trophy - ?
/tt - ?
/unblock /unignore [playername] - unignore a player
/version - check client/flash version
/who [playername] - check a player's current location. their status must be set to online, or else they cannot be found.
/zap_hint - reset all hints (don't use this or it'll bug your skillbook with an annoying tutorial that goes away only when you reset & assign points to a skill)
Display/Quality/Network Commands
/fps [optional: #] - check your current fps [default: 35], can also set a custom fps from 5~60
/makethegamelooklikecrap - set various settings on very low quality at once
toggle_mod_tag - toggle moderator tag on your character (this is just visual)
/cunban /cinvite /cuninvite /cmode - some moderator commands for pvp/trial/etc.
/flags - ?
/hue /bri /des - change the color of something (mod only? idk how to use it's parameters)
/invisible - hide your character. does not seem to work unless higher privileges are needed?
/mmanage - moderator map ui window that lists all players in the current map, allowing you to mute/block a character of your choice and toggle PvP in the map.
/show_hidden - shows hidden entities. does not seem to work unless higher privileges are needed?
/status - moderator-enhanced version. show map name, total player online count (regardless of offline), total monsters/maps that exist in the server.
Playback/Session Tagging Commands
/fw /fww - used for playback mode via My Videos in your official site's profile after using /tag. fast forward or super fast forward.
/tag - save a TAS-like replay of all actions (chat with others/battles) your character has witnessed since logging in.