Hardcore Combat Only

The entire gameplay consists of fighting enemies in different areas, and trying to reach end-game bosses, without ever touching any of the non-combat skills, or ever dying.

There's also a Google Sheet with highscores and some number crunching made by the community of the various players who play this gamemode. Hit up mazunki [they/them]#3247 on Discord if you want to join or view it. Similarly, 8992#7954 has made a completion log script to hide unavailable items, which you can find at GreasyFork. This has since been replaced mostly by Zxv975's HCCO mod.

There is a guide for this gamemode available at HCCO/Guide and feel free to DM Username#7620 on Discord with questions.

Differences

Since we're playing Hardcore, there are some important parts to keep in mind:

No natural HP regeneration/s.
We start with 12 bank slots, capped to 108 (+ slots gained from Bank Slot Tokens after hitting 108 cap).
Harder penalties for being on the weak corner of Combat Triangle.
Permanent death

Template:HardcoreRegeneration

Known alternatives and history

Note: This may not 100% accurate, and should be revised.

While HCCO is believed to have been created by CoolRox, they never played this game mode themselves. From the recorded history, it is not entirely known who was the first player who took this challenge seriously, although it's possible it was bad_name_2009#6633. Regardless, some honorable mentions are 8992#7954, JHawk55#8345, Nomeru#4261 who all played a non-official hardcore version of this gamemode (where regen applied).

After Hardcore was introduced, the only way to actually start a character in this game mode was by doing one of the following:

Spam Lemonade from the Easter egg.
Fight the Confused Pirate, and flee before they hit you (since they have a slower attack time a player with a Bronze Battleaxe would have).
Infinite Birthday Cakes can be obtained if one had completed the Birthday Event, but since the birthday event required non-combat skills, this method would not be possible.

After seeing that HCCO was feasibly possible, Aurora Aquir#4272 joked about a "hardcore 12 bank slots combat only btw" and Drboomtown#0982 was the first to actually try it along with others such as JHawk55#8345, and created what eventually became a trend amongst the challenger-community. There are a few noteworthy players including IzzyYSN#0220, Hashtronomy#9283, Ynotman#8267, and Username#7620.