We have various threads about various online distribution platforms, but a lot of them have gone and dropped far into the forum depth. So as not to practice forbidden dark arts of Threadomancy:
Green Man Gaming has a Battle Trhough the Ages deal going. Mentioning it because it has all the Crusader Kings II stuff going 50% off. That is steam keys.
Personally I did not really like the game, but a lot of forum regulars here absolutley love it.
My own taste in the sale goes more towards the King Arthur games by Neocore: Total War like combat with heroic leaders who advance levels, unlock abilities and become terribly overpowered Add to that chose your own adventure type quests and a very good moral system, that unlocks rewards and options based on a character's position on a two axis chart: morality (rightful - tyrant) and religion (christianity - old gods). Though I usually end up a rightful pagan.
Also at a 50% discount are Blackguard (which I am tempted to get) and some other stuff like Fallen Enchantress.
On Steam itself Bloodline is going really cheap as the deal of the day.
I just don't know how easily that is installed?