This has the potential to be a very long, long list, but here goes 
Parasite Eve 2 and the astoundly abismal The Third Birthday (The original Parasite Eve is one my favourite games of all time)
KOTOR 2 (Mostly because it was extremely rushed)
Dragon Age 2 (What the F did they do to the franchise...)
Grandia 3 and Xtreme (Same thing that DA2)
Alundra 2 (It shouldn't even be called Alundra since there's nothing left from the original game)
Final Fantasy II (Not to be confused with FFII US, which actually was FFIV. Worst FF game of all time)
Sonic Adventures II (The first one was one of my favourite games of the Dreamcast)
Micro Machines V3 and 4 (Why did they forgo the amazing R/C top view? 
)
Shadow Hearts: From a New World (This shouldn't be even considered a Shadow Hearts game)
Medievel II (Extremely dissapointing sequel)
Chrono Cross (Worst sequel of all time)
I think I should stop here...
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
