The latest user interface...
One key aspect I want in my game is to have no set "good" or "evil". You have alignments with certain groups of people, but those are dynamic based on your actions. In Diablo / similar games, you left click on an orc for your basic attack, but you can also safely left click on a blacksmith to sell your equipment. I want you to be able to talk to an orc or attack a blacksmith.
To accomplish this, I've dedicated the left mouse button to "Interact" and the right mouse button to your selected "Tactic".
Left clicking on the ground, an item, or a character is your basic "Interact". If you click on the ground, you'll walk there. If you click on a bag of coins, you'll pick them up. If you click on a chest, you'll attempt to open it. If you click on a door, you'll enter it. And eventually if you click on a person, you'll attempt to communicate.
Right clicking on the ground, an item, or a character does your selected "Tactic". At the lower right of the screen, you can select your active tactic (highlighted in red). If you right click on that blacksmith when the weapon tactic is selected, you'll attack him. You could even click to heal someone that would normally be a foe. (There are keyboard shortcuts for the tactics.)
The tactics are grouped by row...
Row #1: General
Attack - Use your wielded weapon - sword or ranged weapon.
Lock Pick - Pick the lock of a chest. (Chests can be unlocked - single left click opens them. Or locked - require hitting many times with a weapon or use of the lock pick skill.)
Row #2: Arcane Spells (Wizard)
Teleport - Instantly jump to somewhere else that you have vision on.
Flame Wall - Create a ring of fire that lasts several seconds somewhere on the map. Characters within the fire take continuous damage.
Row #3: Divine Spells (Cleric)
Heal - Heal yourself or a target character.
Protection - Create a protective ring around yourself or a target character.
Presence - Show the relative alignment of nearby characters.
Holy Bolt - Request a bolt of lightning to come down on a target character.
Resurrect - Bring a target character back to life.
Row #4: Nature Spells (Druid)
Entangle - Vines come up out of the ground slowing down the movement of those nearby.
You can see the game engine now supports effects that not only draw on the screen but also can affect characters (slow them down, deal damage, etc.).
My preferred role has always been Cleric (and hence why I've already filled out all the cleric types skills), but I've never been a fan of having to choose a specific path and being prevented from stepping outside it. Anyone is able to learn & become skillful at all the tactics. I'll go into stats later; but I'll use those to help balance between someone primarily a magic user vs someone primarily a fighter vs someone that is a jack of all trades / master of none.
Also, I hate warm up times / other preventative measures to keep you form taking advantage of all the skills you know. If you have the Energy, then you can use a tactic/spell. (Doubtful I mentioned this before, but my Mana is now considered Energy - doing a tactic will decrease your Energy. And the cost of tactics varies - Heal costs less Energy than Resurrect for example.)
I've jotted down many other ideas for tactics, and I am fully expecting to have all 20 slots filled for the game. Halfway there already!