2. Mass Effect 3
For the 20-or-so hours it took me to finish Mass Effect 3, the game was a near master-piece for about 19.5 hours of this play time, delivering a thrilling space opera that featured characters we'd gotten to know and care about over the last three games. The narrative was awash in moral ambiguity, but best of all was the thought that everything we'd done in the three games was heading towards an end-game that was going to be heavily influenced by our actions. As it turned out, this was absolute baloney, and the end of the game came down to essentially a binary choice of picking a colour and watching what happens; there was no complex calculation of all of our events throughout the games that resulted in one of countless different endings. BioWare went back on their word and completely devalued the choice system they implemented at the outset, which sparked one of the most infamous fan backlashes in the history of gaming. Fans demanded that the ending be changed - a rather immature request, in my opinion - while the developers weren't even able to stand by their ending, buckling and releasing a DLC that "clarified" the events of the ending. Even so, it still goes down as one of the biggest disappointments of the year, and indeed of the decade, more from a narrative/design perspective than in terms of the gameplay, which was largely as exemplary as ever.