There isn't a single answer—three different metrics each crown a different winner. Here's the breakdown:
Wii Sports — 82.9 million copies. Bundled with the Wii in most regions, it's the best-selling single-platform game ever. Note: Often excluded from "best-selling" lists because it was a pack-in title.
Mario Kart 8 Deluxe — 60.58 million (as of March 2024, Switch only). The highest-selling non-bundled Nintendo game. Animal Crossing: New Horizons (45.36M) and Super Mario Bros. (NES) (40.24M, mostly bundled) follow.
Super Mario franchise — 826+ million across all games (mainline, spin-offs, mobile). Pokémon franchise ~480M (games only), Zelda ~130M.
Mario Kart 8 Deluxe also leads digital sales (Nintendo doesn't publish exact splits, but >50% of recent sales are digital). Tetris (Nintendo-published versions) has hundreds of millions across Game Boy, NES, and mobile—but fragmented across publishers and platforms.
| Metric | Game | Units |
|---|---|---|
| Single SKU (incl. bundles) | Wii Sports | 82.9M |
| Standalone purchase | Mario Kart 8 Deluxe | 60.6M |
| Franchise total | Super Mario | 826M+ |
| Single game (non-Nintendo pub) | Tetris (all) | 520M+ (est.) |
Bottom Line: If someone asks "What's Nintendo's biggest game?" say Mario Kart 8 Deluxe (modern, standalone, still selling). For "biggest ever," Wii Sports. For "biggest franchise," Super Mario.