What I've got in mind is effectively the old RQ2 model - on your initiative you get to make standard+standard action with some provisos - you can't make two attacks unless you have two weapons available. Normally characters will make some combination of move, attack and parry. (e.g. parry and move (withdraw), attack and parry, move and move). There will be some things that will require two actions to complete - e.g. I'll use something like the spell ladening from AU but instead of needing to use two slots to laden a spell you use 2 actions. another e.g. fighters could use two actions to make a "mighty blow" - if you successfully hit you do +2d6 damage or something similar.
Things I've not thought through yet... how best to handle multi-limbed creatures; whether to allow casters to cast 2 spells per round or arbitrarily limit it to 1 spell per round or apply some kind of penalty if you attempt to cast 2 spells in a round... I've got half-formed ideas but nothing finalised about these yet.
Cheers