Twin: Have you thought any about this:
Use the d100 percentile roll as a multiplier. Multiply whatever base stat is being used by the die roll taken as a percentage, and turn chance to hit into opposed rolls. Here's an example:
Player 1 has 120 AGI with no bonuses to dodge. Monster 1 has 95 DEX and a weapon with +25 Hit. Monster 1 has a base to-hit of 120, Player 1 matches that. Player 1 rolls 34, Monster 1 rolls 56. Player 1's effective AGI for the attack is 1.34 * 120 = 160.8 = 161. Monster 1's effective to-hit for the attack is 1.56 * 120 = 187.2 =187. The monster hits successfully, and you proceed to roll damage and check it vs. the player's resistance and health.
Eh, maybe it's complicated, and maybe there's a problem I didn't spot.
'cause the d100 as a flat addition to the relevant stat is going to work, but only for a little while, unless you're capping ability scores at 100 (which is sort of silly, because everyone would max out their two or three main stats fairly early on, and would also leave you nowhere to go with monster and equipment scaling).
Unrelated: How are you going to manage Switching? It was pretty damned core to SAO's combat, arguably even more so than Sword Arts.
e: Also, I'm down for a playtest this afternoon.
I actually think that might be much fairer. Anyone else have an opinion before I decide to switch it?
Lol yup that works then im doing a mix of tank and a few supporting effects to make enemies easier to hit or make them less accurate.
Twin how will loot work? Individual loot for each person or joint loot for us to distribute amongst the group?
EXP and Money are going to be split evenly between party members. Loot items will go to individuals, but they may choose to give them to others.
Admittedly, it's less pressing if Twin isn't going to use the mechanic where Sword Arts briefly self-stun after you use them. That's one of the reasons why Switching was important, it stopped mobs and bosses from pasting your buddy after they used a Sword Art on them.
Sword Skills will have you frozen for 1 turn, to stop them from being used every single turn. Switching will be allowed, and let you swap spots with anyone within 3 spaces (2 spaces diagonal).
Also, making a map. RPG Maker VX Ace Lite has a limit on sprites, so I may have to figure out something else to represent players and monsters...