Nintendo Switch Online subscribers who opt for the Expansion Pass can access a selection of Sega Genesis titles alongside the service's traditional NES and SNES library. However, the Genesis catalog contains dozens of notable releases, and only a fraction have been included so far. The following ten games are widely regarded as essential entries that remain absent from the service.

10. Boogerman: A Pick and Flick Adventure

Originally released by Interplay on November 18, 1994, Boogerman blends platforming with gross-out humor centered on a comic-book hero who defeats foes using burps, farts, and boogers. The game features over 20 levels, puzzles, and boss encounters, supported by detailed character designs. Though it appeared on Nintendo's Virtual Console in 2008, it has not been re-released since.

9. Championship Pro-Am

Developed by Rare and Tradewest, this 1992 title expands on the NES original R.C. Pro-Am by supporting six simultaneous racers, enhanced visuals, and a revised letter-collecting mechanic. While high scores are now saved and the game was included in the 2015 Rare Replay compilation, it was omitted from that collection and has since faded from public awareness. Its inclusion in Switch Online would reintroduce it to modern audiences.

8. Ecco: The Tides of Time

The sequel to Ecco the Dolphin, released on August 25, 1994, continues the underwater adventure with new mechanics such as the Pulsar power-up for sonar attacks and the Metasphere transformation ability. The game emphasizes exploration through scavenger hunts across expansive stages, though its open layout can occasionally lead to disorientation. A remaster is currently in development, which may increase demand for its availability on Switch.

7. Forgotten Worlds

Originally an arcade shooter launched on November 17, 1989, Forgotten Worlds was adapted to the Genesis by Sega, reducing its nine stages to seven and adding long-range weapons and an auto-fire function. The control scheme was revised to use buttons A and C for directional rotation. A Virtual Console version existed until the Wii Shop Channel closed in 2019, after which it became inaccessible on modern Nintendo hardware without legacy devices.

6. General Chaos

Released on January 13, 1994 by Game Refuge and published by Electronic Arts, General Chaos is a real-time strategy game exclusive to the Genesis. It features 50 battlefields supporting head-to-head and cooperative play for up to four players, viewed from an isometric perspective. The game is noted for its vibrant, cartoonish visuals and diverse arsenal of weapons, including rocket launchers and flamethrowers. Despite its critical acclaim, it has not been re-released on any modern platform.

5. Phelios

Originally an arcade title from Namco in 1989, Phelios arrived on the Genesis in 1990 and reached European markets in 1991. It is a vertically scrolling shooter in which players control Apollo, the Greek sun god, riding Pegasus to rescue Artemis from the titan Typhon. The game allows both rapid-fire and charged shots, and permits limited damage tolerance. While it is available through Hamster's Arcade Archives on Switch, the original Genesis version remains part of the missing library.

4. Splatterhouse 2

Developed by Now Production for Namco, Splatterhouse 2 launched on August 4, 1992 as a follow-up to the 1988 arcade original. The game continues the story of Rick, who seeks to rescue his girlfriend from a supernatural fate by battling through eight new stages using fists, feet, and various weapons. It includes a password save system in its English version and was previously released on Virtual Console and the Genesis Mini 2, indicating prior availability on Nintendo platforms.

3. Ranger-X

Ranger-X, developed by Gau Entertainment (later Nex Entertainment) and released on May 27, 1993, is celebrated for its detailed environments and innovative use of a six-button controller. Players control an exosuit-wearing protagonist fighting Rahuna forces, with mechanics including short-duration flight and multi-directional weaponry. The game's dynamic action and technical demands made it a standout title among Genesis fans, who have expressed interest in its inclusion on Switch Online.

2. Super Skidmarks

Originally developed by Acid Software for the Amiga in 1995, Super Skidmarks was adapted for the Genesis by Codemasters, limited to the European market. It features six-player competitive racing with whimsical vehicles such as wheeled cows, set across intricately designed tracks. As the second installment in a brief series that concluded with Ultimate Super Skidmarks in 1998, its quirky multiplayer focus has been cited as a reason for renewed interest.

1. ClayFighter

Released in December 1994 by Interplay, ClayFighter emerged during the fighting game boom following Street Fighter 2 and Mortal Kombat. The game features a cast of clay-animated characters, including Bad Mr. Frosty and an Elvis impersonator, combining violent combos with juvenile humor. It required a six-button controller for optimal play and was the final Genesis entry in the series. While earlier entries have appeared on Nintendo platforms via Virtual Console, the Genesis version remains the only one not currently accessible through Switch Online.

The absence of these titles from Nintendo's retro offerings reflects both the breadth of the Genesis library and the selective nature of digital re-releases. Their inclusion would provide players with broader access to a pivotal era of Sega's hardware legacy.