A free, PC-only Assassin's Creed: Origin update has added the Animus Control Panel, designed to let you "hack" the game by fiddling with 70 different sliders. You can now run four times the normal speed, hit twice as hard, and tame more animals at any one time, creating an army of hippos to destroy anyone in your path.
I like that you can use it both for shenanigans—reducing enemy speed to 25% while you zip around them like an annoying fly—or to tweak the game slightly so that it suits your playstyle. If you enjoy a more arcade-y feel, you could up attack speed to 150% and reduce stun time. Or if you want slow, meaningful combat, you can slow down swing speed, increase damage and limit health points.
Ubisoft says it might be "overwhelming" for some players, so it's created a few presets to get you started. Hardcore Stealth, for example, will increase enemy senses so that they'll detect you at the slightest sound, but you'll be able to assassinate them in one hit.
If you enjoyed the game but got all you could out of it, then it could be fun to jump back in and twiddle with the sliders for half an hour. Players are sharing their presets on the Ubisoft forums, in case you're looking for inspiration.