Wii sports. It was such a system seller that some people did not know that the Wii could play other games.
Will list the games that got me to buy/wish for each console I have had significant access to..
NES - Super Mario Bros 3
SNES - Zelda a Link to the Past
Gameboy - Tetris
Game boy advance - Warioland 4 (Mostly played Pokémon Crystal instead since I found out that I did not like Warioland very much)
PS1 - Crash Bandicoot
Gamecube - Mario Kart Double Dash!! ... and Zelda collectors edition that came packed in. Oh that deal will probably never be beaten.
PC - Warcraft 3. Upgraded the old famiily PC that I had taken over to be able to play this
PS2 - Resident Evil 4 (played it on Gamecube first, but when I moved out the Cube was left with the rest of the family and I simply needed to play this more)
DS - Warioware Touched
Wii - Zelda Twilight princess
PS3 - The last of us
3DS - Nothing, just got into some money the same week it got released and bought it.
New 3DS - Majoras Mask 3D
WiiU - Super Mario Maker
Switch - Zelda breath of the wild (Even bought the game before the console)
PS5 - Massive list of PS4 games and 4K blu-ray player