major weapon customization. Like, have weapons level up and increase stats, have them able to combine jewels from sockets/socketing, have them able to have enchantments and elemental affinities, able to be able to use either 2 one handed, able to use daggers for 2 hands, dagger plus main hand, or one two handed, or 2 shields. Have equipment be made from several levels of metals, light/soft/medium/heavy/hard/whatev.
for material gathering, do something fucking different than runescape or mabinogi. not click and wait three seconds, click and wait, click and wait.
like have three "slot" like bars, where the cursor moves back and forth fast, and have to click on a certain position. Getting a good spot has a higher chance to get good items higher level gathering has the cursor move faster. Additionally, have the option TO do a runescape-like thing, for the lazy bastards, but the chances to get good items are much less compared to getting the right place.
Fishin's easy. Just wait, put the exclamation sign when there's a fish, etc. add some stuff if you want.
Have random fishing and mining in dungeons, with higher chances, so to reward people are carry around a pick for no reason
make every tool a weapon, with certain powerful skills being unlocked when using shitty tools/weapons
have an archery competition. Add wind speed and direction. Check out that minigame from quintessence for an idea of what to do.
have a similar system from mining for tree cutting, but have it only go up and down one time. when it's at the top, click, and you have a higher chance of retriving material. Again, have a pass system like runescape, but moderately lower chances each swing.
Be able to create quests of your own for other characters to do. Kill an player, gather items, whatever. I don't get why no one's done this. Adds a shitload of replayability when you have thousands of gold and you set up 2 quests for 2 clans to kill each other. Additionally, you have to sacrifice your own experience and money BEFOREHAND, so if you never log back in the quest still works.
Make the level cap VERY high, with level ups giving smaller stats, and easy to level up (but not like 2 enemies and level up at the beginning). It's super fun leveling up, but boring when it takes FUCKING FOREVER to level up, spend all the points in 12 seconds, and have four more days of grinding.
Have subclass system, and then an extra subclass. Adds an extra point or two to a stat when leveling up. And then specialization and another subclass later, although NOT as endgame content for any of those. Besides fashion customization, actual statistic customization are one of the coolest things to have, seriously. It's enjoyable for casuals, and harcore players have much more strategizing and crap.
Being able to "equip" a couple of skills at once, like four or five at a time, while certain areas, like towns, allow you to change skills. Adds another level of strategy to the game, so that we don't just spam exactly what skill is needed for the dungeon. Also, equipment to increase skills lots.
.....too much?