Metroid Prime Hunters
Some later portions of the game are really markedly difficult, which I would regard as 'challenging' if it weren't for the repetitive and monotonous nature of continuing after death. Especially in areas where death comes swiftly and instantly (for instance, a morph ball sequence where crushing pistons will not damage you, but kill you completely). As I've said, it lacks the storytelling elements that made Metroid Prime and 2 epic adventures; the 'hunters' theme is a neat idea, but really no match for running antagonists like increasingly powerful space pirates or Dark Samus. It also has the same environmental issue as MP2: Echoes, namely that most of the game's areas look extremely alike. There is a hot world, but only one or two rooms actually have lava; there is a cold world, but the ice is often encased with electronic regalia; and there are two space stations. The bosses have the same problem - there are eight Octolith bosses, but only two types of boss and four 'versions' of each. Plus a final boss, but that thing was so mind-numbingly easy I'm hesitant to count it. Hunters and Echoes also share the rather trite concept of collecting items; in Hunters, you must find three Alimbic Artifacts to unlock each of the eight Octoliths.
There are six highly unique alternate weapons, which would be good for variety, except most of them are pretty pointless. The sniper weapon is used in some puzzle solving, and occasionally a fire enemy will be extra vulnerable to the frost weapon or vice versa; by and large the alt weapons are meaningless in single player. They're probably more useful in multiplayer (since they can have secondary effects like freezing or distorting vision), which by the way seems like a solid offering, but I have little interest in it (not a shooter fan). Some stuff was fun and some stuff not so much, but the inconsequential ending made it very clear that Adventure Mode was not the primary focus of the game design.
Progress: Complete