I have this idea for turn based combat with planning for more than 1 turn (with mechanical benefits if you don't change your plans).
Each character has X action points each turn (let's say 10 but it will be based on attributes), and each action has cost in action points, but if you plan it for this round it's multiplied by 3, if you plan it for the next round it's multiplied by 2, and for 2 rounds later it's multiplied by 1. Action points are spent when you plan, not when you execute (so if you want you can do nothing for 2 turns but plan and then in 3rd round do stuff for effectively 10*3+10*2+10*1 AP).
Example:
- 1 step forward/left/right/back costs you NOW 6 action points if you plan it for this turn. If you plan if to the next turn it costs you NOW 4 AP, if you plan to do it 2 turns later it only costs you NOW 2 AP
- turn 90 degree costs 3/2/1
- normal attack costs 6/4/2
- strong attack costs 12/8/4
- riposte costs 6/4/2 (parries 1 attack and attacks, but doesn't do anything if you're not attacked)
- feint costs 3/2/1 (wastes 1 riposte or parry)
- parry costs 3/2/1 (parries 1 attack)
etc.
Turns are executed simultanously (like in Into The Breach), you have 10 AP each round and each round you can use your current AP to change your orders for this round, next, and the round after that. But editing orders scales the same as adding them. For example if 3 rounds ago you planned to do 5 steps forward in this round (5 steps * 2AP = you spent all 10 AP these 3 rounds ago on this) and last round enemy placed a trap on your path - you can only edit 1 of these steps because it costs 6 AP now to change that and you only have 10 AP. So your best option is to add order to step ssidewayss or turn before that 5 steps forward.
If you predict what happens you can weave between the enemies hitting them left and right while they swing at air. If you don't - you bump into someone in the middle of your move and they hack you to pieces
Some enemies will be very predictable, especially animals etc - so after a while you can kill them no problem by abusing their patterns. But more intelligent enemies will choose randomly from several tactics and you have to plan for several possibilities.
Later you get skills like seeing enemy orders for the next round or action boost where you can move some points to the next round (so you have 5 AP to spend this round and 15 AP the next round - so you can be more reactive).
My problem with the idea is:
- how to explain it to the players
- what the UI should be
And especially the UI is hard, I prototyped a few things and it's always ugly and inconvenient. The most convenient was basically a command line and list of orders looking like BASIC program besides the tactical map. I don't think that will work in a game