AC 1, 2, and uh either Brotherhood or 3, followed some semblance of a storyline, and were great. Each improved upon the last in a pretty meaningful way. For this reason, I'd recomend playing them in order up until that point, as you'll notice the missing mechanics if you don't.
Unfortunately, the original AC franchise was planned as a trilogy, but the story has gone to hell since they made the decision to scrap that vision and milk the cash cow.
I haven't played them seriously since maybe AC3, as they felt like reskinned clones each iteration, with the addition of terrible bugs/patches/dlc and the rest of your typical fair for modern day releases that took weeks and months to fix. But hey, thats what you get when you churn out a whole 'game' every few months.
ANYway, AC:O looks like they have gone a new direction. Made it a bit more RPG-y, and less 1-hit-ko-every-enemy-and-boss-with-hidden-blade (in the first handful of games there was little reason to have anything but the starter hidden blade equipped as the doge/counter move was always your highest damaging attack AND fully mitigated any damage when timed properly). Which, if you ask me, sounds like it'll make for a better game altogether
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