I'm left wondering one thing: how would I possibly adapt this for a turn based game?
In every turn based game I've seen evading attacks are represented by a random chance for an attack to do no damage; a "to-hit" rating. If I combine that with Bushido Blade style one-hit kills then a character's life is entirely in the hands of the Random Number Gods ("The only people who should roll dice are those who are prepared to roll a 1.").
Are there any non-random ways to represent evasion in a turn based game?
Quest 64 was turned based. During your turn, you can move freely around a small circle of movement area, within a much larger circle of the battle area. When it was the enemy's turn, he uses a move that physically shoots out some kind of magic, and you regain your movement for a split second to physically dodge the magic.
There was also a tiny percent chance of randomly missing ("Miss!"), but that percent would get alot higher if you were farther from the physical magic attack, and wouldn't even bother saying "Miss!" if you clearly weren't touched by the magic.
Here's the first boss battle in the game: [youtube]
You'll notice on the few misses of the player, his attack was aimed slightly short or to the side, and so had a greater chance of randomly Miss!-ing. You'll also notice that the boss's attacks are so far off (because of the player dodging) that it doesn't even bother saying "Miss!".
Enemy attacks sometimes have shapes to them - in the video above, the boss mostly just shoots beams of fire-magic. You can either dodge to one side or the other, or you can perfectly align yourself inside the tunnel-like beam, and it'll pass around you - pretty difficult to do. If you get too close to the boss, he'll switch to another attack where he causes earth spikes to shoot up from the ground all around him in an AoE. If you're careful, you can run closer and be protected in a tiny area around the boss himself, where the boss doesn't get hurt and where you can also not get hurt.
This particular boss is rather easy to dodge, but that doesn't apply to the entire game. Some enemies do things like cause avalanches of rocks to fall down, and you have to dodge them all, or else shoot semi-homing arrow missiles at you, or have other methods of attack.
The easiest thing is to keep your distance and blast away with magic, but that's not always an option, and even then you can still get worn down by enemies as they get hits in here or there, and as you run low in mana and don't want to waste items. Melee attacking requires you to get real close, but each melee attack gets you some mana back.
Here's the second boss battle, after several more dungeons - maybe an hour or two gameplay later: [second boss]
At the end of each turn, where you end up is the center of the new circle of movement you have.
You can get magic or use an item that temporarily increases the radius of your circle of movement.
If you, over several turns, move to the edge of the entire battle area, you can escape battles (except for boss fights) if you intentionally go outside of it and press the 'Action' button.