>>96011836
Not one you pay for, but Corporate Era in Terraforming Mars. It adds a whole bunch of cards that are way more powerful than average, adds a lot of random card draw (significantly reducing the impact of drafting and increasing variance/luck factor) and makes an already long game take even longer, while adding almost no new strategic elements (almost all 'interaction' in CE is braindead simple). I genuinely don't understand why people insist on playing CE instead of non-CE (with at least Preludes included, of course).