For the second category, I would suggest C&C Renegade.
First, to understand why it failed, you have to look at how C&C Renegade was developed. The player was to take the role of a commando from the original Command and Conquer - powerful in its own right, but particularly vulnerable in others. The early versions of the game reflected this: Gameplay was as much about tactically picking which fights to take and how to take them as it was about straight-up shooting. I hate to make the MGS comparison, but it felt like a somewhat more shootey version of that game.
Unfortunately at some point they decided that no, they needed a straight-up explode-'em-all shooter - with tanks exploding, helicopters being shot down, and enemy troops dying by the dozen. The graphics engine also went through an inexplicable change which - aside from seeming to lower the quality - left enemies and allies alike wearing almost comically-brightly-colored jumpsuits rather than the more reasonably-colored camo that had been displayed previously.
The response was to add an entirely new style of gameplay. If the battles were to be huge, then resources would have to be the limiter: They set up a system where players received resources with which new equipment, upgrades, and vehicles could be purchased; resources were awarded for taking down enemy troops, buildings, securing objectives, etc. If player choice couldn't be about stealth vs. brawn, it could be about choice of weapon and tool for the fight.
And then they failed to use it in half the game. What remained was a painfully repetitive single-player that didn't use any of this tactical choice. You could lug around every weapon in the game at once, although only a handful were used on account of being hilariously broken.
Multiplayer still kept with the tactical choice concept, and remains surprisingly fun - the ability to reconfigure your team on the fly, including vehicle options, was very enjoyable. Unfortunately, the multiplayer UI was also tough to figure out - and so well hidden I've met a fair few people who didn't realise the game even had a multiplayer option.
tl;dr - developers change the game concept repeatedly, then fail to use their star mechanic in half the game - and hide the better half so well people missed it entirely.