Shinobi 2 for Game Gear was a childhood favourite even if I didn’t have any batteries and just had to hang out near an outlet to play it. I booted it up on my Analogue Pocket recently, and it’s still super fun! I enjoyed a bunch of games on the system, but that’s the one that feels like an all-time classic to me.
Yes. Absolutely. Shinobi 2 for Sega Game Gear is an all time classic.
It's a shame more people don't encounter it when exploring retrogames. It's so easy to assume the Genesis versions of each title will be better, and skip trying the GameGear version.