I briefly tried the browser-based version of this game some time ago but it seemed overly complicated and I’m not fond of permadeath in the first place (losing 10+ hours of progress to a missclick is beyond annoying). However, after buying the GOG version on whim one day I played again and this time around it become quite engrossing.
There’s a bunch of things to unlock/collect and with the ‘Adventurer’ option enabled you don’t have to worry about a single mistake erasing everything. That said… I would actually suggest playing on ‘Roguelike’ once you’ve unlocked everything you want to; the second half of the main campaign is nowhere near as good as the first half and it’s more fun to start a new character than slog through that mire. Getting started is really the hardest part, and this area guide does wonders to make things more accessible. You can also find immensely helpful class guides on that forum as well.
As far as the DLC go:
– Ashes of Urhrok is the cheapest and also adds the least to the game. The new race and classes are really the only reason to pick it up.
– Forbidden Cults on the other hand adds quite a bit to the game. In addition to the races and classes (one of which is a pain to unlock) it adds a large number of fully integrated new areas and even a new ability line to the Wyrmic class.
– Embers of Rage adds a sequel campaign (that’s about 30-40% the size of the main campaign) which is decent enough if you don’t mind the accelerated leveling speed and hamfisted gold/merchant situation. Its endboss is a giant difficulty spike though. What’s far more interesting is the crafting system it introduces, which is a lot of fun to play around with.
So I’d say definitely pick up Forbidden Cults, but only grab the other two if/when you want to try something new.