Final Level: Reckoning
Why It Sucked: Crysis's ending is so clearly unfinished it actually hurts. Anyone who didn't watch that final cutscene and assume that there was at least one more mission must have read the strategy guide beforehand. It didn't help that the sequel had jack shit to do with this plot.
How We Would End It: Don't end on a cliffhanger if you're not going to follow through—the resolution could have easily stood without our heroes heading right back into the fray, and thus leaving us hanging.