Well, it doesn't hurt me to pick up a Dark Souls game next time it hits a big sale. I'm not sure what these have been discounted to, but the Winter Sale should knock it down quite a bit. Should I try 1 or 2? I don't own a controller, so which is easier with K/M?
P.S. I'll play a spell slinger, if that makes a difference.
I´d highly recommend getting Dark Souls 2: Scholar of the First Sin over the predecessor.
DS2 plays just fine with k/m once you rebind some keys, without the need for fan patches.
Moreover, it provides quite notably more interesting and varied experience for spell casters (more and more varied spells, weapons/shields with spellcasting abilities).
It´s also a bit more straightforward in terms of providing you with spellcasting arsenal, whereas DS1 locks some of the crucial vendors in places that are rather easily missed on an unspoiled first-time playthrough.
DS2 SotFS is also a lot bigger than DS1 and levelling comes at a bit faster pace which means you can quite comfortably branch out into another spell school if you feel like.
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While I´m at it, even though I don´t want to get into the "twitch-or-not" debate per se, I think it bears pointing out that Souls games support multiple play styles and these can rather substantially differ in terms of required/encouraged "twitchiness".
Characters built towards dodging with little protection certainly tend to be more demanding on fast reflexes than heavily armored ones liberally relying on shields, characters utilizing fast weapons (especially when geared towards high counter damage) tend to play twitchier than characters relying on slow heavy hitting stuff, ranged characters (spellcasters mostly, though in DS2 bow-only characters are viable too) are in general less demanding on reflexes than melee ones, etc.
Anyone who wants to have own reflexes challenged can play the way which should facilitate it, but for anyone who necessarily doesn´t there are various ways of mitigation, after all the combat in these games isn´t just action - it comes with the RPG aspect too
(which, among other things, includes building own character towards the intended play style - trying to play a "high-twitch" character with equip load causing slow roll or slow stamina regeneration is not a particularly good idea and so on).
I suspect that at least partially some of the twitch-or-not debates stem from ignoring/forgetting the above. Obviously everyone has different thresholds for what is or isn´t reflex-demanding, but that´s besides my point.