A few additions would be very valuable to the game. I'll suggest the addition, and then the reason why I think it'll be valuable.
Consequences of Death
Firstly, I think an important new feature to be added to the game is consequences, namely the consequences of death. At the moment it's far too carefree, and that reduces the intensity of the game. Therefore, adding penalties for death, as well as ways around it, and items that help offset this penalty would be really interesting, and add the use of extra items (perhaps such as potions) to increase the caution and excitement of the players.
There are multiple ways the penalty of dying in game can be implemented, and I'll just name a few:
1- Loss of EXP and Gold (the penalty can be relative to the player's level)
2- Loss of certain items (items that are only available through tough quests? therefore, requiring the player to retry the quest if they fail the death-less attempt)
3- If the player isn't able to meet the Gold/EXP penalties for death, they log in Death's domain (instead of battleon) and have to navigate through there to find their way out (allows for introduction of Death's domain and his quests).
4- The affect of death can also be made unique depending on the player's alliance and rep in regards to Good/Evil, Dage, Nulgath, etc.
5- Time based penalties can also be added, for example, upon death, the player will have a 24h DoT (very small) placed on them during battle due to recovery from death's fatigue. Or something like, they gain EXP at a slower than usual rate for 24hours. These are just examples, but I think you get the idea.
The reason why I suggested this isn't to put people off the game, rather make them value being 'alive' (in the sense, that you're not losing to a monster). Not only does this force other stronger players to clear areas for weaker players, but in tougher zones, it forces players to work together. It also brings in the value of the 6th slot items such as potions and scrolls to improve the survivability of the players. It provides a genuine experience of going out to adventures and risking your life in battles, etc. etc.
Monster AI update
Another feature of the game is that it is lacking in unique regular monsters. Sure there are plenty of unique bosses, such as Escherion, Kitsune and Binky. However, the everyday fodder targets become somewhat more of a nuisance rather than an interesting encounter because of their very VERY basic structure. I think regular targets need to have unique properties so that the class skills are not only useful against bosses, but also against regular targets. Here's an example using dage's 'minions' in Evil war nulgath:
- Should have far higher haste, should be able to dodge a few attacks
- Attacks should be relatively weaker, but much MUCH faster.
- Should be able to place a moderate DoT on target "Bleed effect"
- Slower attacks but should hit harder
- Poison damage? DoT?
You get the idea of where I'm going with this.
Furthermore, I think all monsters in game should have an aggressive AI, and their targeting should be based off player level. Therefore higher the level, the more of a natural 'focus' you have on the targets in the room- this can be balanced by, the number of deaths (or recent deaths) offsetting the focus the player has on AI targets. I think adding this forces players to work together, and forces higher level players to require working with others, and use items.
I'm not fully sure about this one to be honest. But I do remember a time when AQW's MP and HP values were based off the INT and END stats. I think with the current power level of players, this would be a great opportunity to bring that system back. Spell based classes having higher MP and lower HP, whilst the STR/END based classes have higher HP and lower MP. I think it would be valuable in terms of overall game usage as it'll force the players to equip their required slots, regarding potions, etc.