ActRaiser on SNES is a classic genre bending game half side-scrolling platformer and half SimCity town management gameplay.

Oh, Nier Automata for sure.

I dunno, a fighting game that emphasizes vertical movement and where characters don't have proper HP sounds genre bending to me. Especially by early 1999 standards.

EDIT: Just remembered that Knights in the Nightmare exists. It was a DS game that combined strategy, RPG, and bullet hell mechanics. Undertale, though less exotic, deserves credit for using bullet hell mechanics in the format of a turn-based RPG.

The Black & White games had elements of City Builders, RTS's, and pet sims.

The entire Rogue-like subgenre is all about adding Rogue elements to completely different genres, like Metroid-likes, platformers, dungeon crawlers, strategy games, etc.

Brutal Legend has been described as an open world action-adventure game with rhythm game and RTS elements.

Katamari Damacy is... Katamari Damacy.

Games like Nights and the old Bionic Commando are very different from what one would expect from a platformer, being focused on aerial movements and never jumping respectively.

Devil's Third on the Wii U was a FPS with third person shooting and hack n' slash mechanics. I think that qualifies.

Warhammer 40K Space Marine. A little bit of Gears of War and a little bit of Dynasty Warriors. All chaotic fun. I know nothing about the Warhammer or 40K universe really but the game is just plain fun as hell. The choice is yours most of the time. Go in all guns. Hack and slash your way through or both.

Does Stellar Blade fit into the discussion?  I haven't played it but really want too.  Seems like Nier with some Bayonetta and touches of Sekiro?  Or am I just way off?  

Found another but it has yet to release. Looks fantastic.

I would classify Minecraft as a game that sort of doesn't have a genre. Is it a farming sim? Survival sim? Life sim? Survival horror? Is it a sandbox game? An action game? It can be just about anything.

Jurassic Park (SNES) maybe?
It's a top down adventure game when you're outside, and is more akin to a first person shooter when you're inside.

I'm freaking LOVING Dave the Diver rn. Been putting it off and finally saw it discounted so jumped on it. It's funny, I threw it out there to my cousin Dave as a semi-joke, "found your game!" Then he ended up playing it I think largely from me bringing it to his attention, and he rec'd it to me saying it was one of his favs of like the last 5 years. So I had to get it. It's definetely one of the most rewarding games I've played in years. I love how almost every aspect of it is fun, exciting, and satisfying. Usually even the great games have slow/dull/insignificant segments, but Dave is just constant fun. Both the sushi shop management and the more action-based diving portions are a blast in their own way.

I guess Minecraft if that counts. Had such a blast with the Alpha version back in the day. Just endless potential between the action, teraforming, crafting. I love games that maximize player freedom, progression, creativity, and customization and Minecraft has those qualities spades. 

I think the next genre-bender I'm going for is Golf Story and/or Sports story.. Are these games rad? Are they worth it?