Here is a collection of ROMhacks and fangames I have played that match/exceed the level of quality that their original counterparts set.
I highly recommend checking these projects out if you like the original games! Links to the download pages are attached for your convenience.
Every item, character, trinket, and pickup is locked from the start with this mod! On your first run you will only have Breakfast and bombs on your side to kill Mom! This Isaac difficulty mod has quickly enraptured me and I will be playing it non-stop once it gets its 1.0 release.
This Pokemon fan-game lets you fuse any 2 monsters together, taking a type, moves, and stats from each 'parent'. The teambuilding in this game is like no other, as you will have an exponentually higher number of options available to you compared to a normal Pokemon game! I highly recommend this fan-game to anyone who enjoys engaging with the Pokemon battle system and wishes that the main-series took greater advantage of that system's mechanics.
This is Plants vs Zombies 2 but with none of the fluff. Enjoy using plants that are gated behind microtransactions in the main game for free, as well as some original plants! Every plant has a distinct niche from each other and many of the redundant vanilla plants have had their abilities changed to make them more unique. The difficulty starts out pretty casual, but be warned! By the end of the 200+ level campaign the levels will test your abilities with the utmost scrutiny. I've made a video about my journey beating the hardest level in the game, viewable here!
Yume 2kki Online is a fan-made sequel to Yume Nikki that can be played online in your web-browser. If you haven't played Yume Nikki before, its kind of hard to explain its appeal, but I would highly recommend at least trying either game, both of which are available on the linked website. You can choose between playing with other players turned off or with other players and chat visible. I really recommend the latter, as finding other players in the middle of nowhere and going on exploration missions with others really added to the experience for me.
This hack of Pikmin 2 is a shitpost of the highest quality. Imagine a repainted mod, but also with original levels and mechanics! It's a fair bit harder than vanilla Pikmin 2, so if you're down with that you'll probably have a great time playing this hilarious and YTP nostalgic hack.
Unlike Bikmin, Pikmin 251 plays it straight for the most part. This is basically 'Pikmin 2' 2. As this was the first major rom-hack of Pikmin 2, its a bit less ambitious than Bikmin, but I would still recommend this to anyone that enjoyed the original game!
This enhancement hack of Pokemon Platinum builds on top of the already amazing campaign to make it the best it can be! Platinum is already my favorite official Pokemon game and this hack made me love playing through Sinnoh even more. All pokemon from generations 1-4 are catchable, sidequests are added for catching the many legendary pokemon, opposing trainers are much stronger, moves/abilities/typings of pokemon are updated to generation 7, and more. The recent Pokemon games have gotten me pretty down when comparing them to the classics and thinking about the path the series is headed down, but playing Renegade Platinum was a breath of fresh air for me, and reminded me what I love so much about Pokemon!