If you already pay for NSO + Expansion for N64 games, the Genesis NSO is a no-brainer. If you want permanent ownership, buy the Classics Collection.
Critical point for modders: Even with the NSP installed, you play the games without a valid Nintendo Account with Expansion Pack entitlement. Some CFW setups bypass this, but that’s legally grey. SEGA Genesis - Nintendo Switch Online -NSP--US-...
Hold down ZL or ZR to rewind time up to approximately 40 seconds. This is a lifesaver in brutally difficult games like Contra: Hard Corps . If you already pay for NSO + Expansion
A proper dump of this NSP (Title ID typically starts with 0100C9A00ECE6000 for the base app) contains: Some CFW setups bypass this, but that’s legally grey
The file you’re referring to ( SEGA Genesis - Nintendo Switch Online - NSP - US ) is the of the official software, typically shared in console modding/piracy circles .