There are games that can give me the final push to get a console/PC upgrade, but only if there are other previously released games for that platform that interest me.

But otherwise no, I don't buy a platform for just one game/franchise. I personally find it ridiculous.

I bought a PS2 just for Persona 4, I was a supporter of the Dreamcast and Gamecube.
I bought a Xbox360 just because Gears of War looked so impressive!
I bought a Nintendo64 just for Zelda

Now I would have bought a Xbox One for Gears of War 4, but since its coming to PC history will not repeat itself :)

Zelda

New jak and daxter from naughty dog

I buy whatever has Zelda. That means I'll get any Nintendo system by default. If Nintendo would stop making consoles, I'd get whatever system gets Zelda, regardless of hardware-maker.

I would buy a console for a full blown super high budget Pokémon MMO with a game world as lush and lively as the pokémon world is presented in the movies

other than that it takes several great titles to convince me to buy in

Mario Kart, only reason I got a WiiU.

I bought my PSP for Metal Gear, and I bought my PS3 for the same reason. But the PSP had a few Metal Gear games like Portable Ops, Acid, and Peacewalker(all of which I owned and beat, except for Acid 2 which I didn't beat cause it was... odd).

In hindsight I think the PS3 was a foolish purchase in 2008, since I did so little gaming before maybe Arkham Asylum came out, but it's still in working order and my gaming has definitely ramped up since then.

I wouldn't buy a console just for a single game nowadays. And definitely not for another Metal Gear.

I would buy a NX just for a true sequel to Paper Mario TTYD! Maybe one day I will finally get it........

I can never justify buying a system for one game. Maybe renting or borrowing it, but not buying.