The new Nintendo Switch Online update adds four new games to Nintendo's classics library. It was originally supposed to just be three games, but a fourth surprise game was added in the form of Gradius SP.
The SP in Gradius means that, like The Legend of Zelda SP, there's a little boost to give players a leg-up. In this case players will start with a leveled-up Vic Viper ship that starts at the fifth level. These aren't cheat codes per se but they help get players straight into the action.
The other three games added in the Nintendo Switch Online are Metroit, Might Bomb Jack, and Twinbee, all previously announced for the service. In Japan players got an SP version of Mario Open Golf though there aren't a lot of details of what the SP version added.
Nintendo Switch Online comes with access to a library of classic NES games. Nintendo began offering SP versions of classic games starting with The Legend of Zelda which gave players some Rupees to start with. The classic library includes just NES games so far, but having a Nintendo Switch Online subscription also has other perks like being able to purchase an exclusive NES wireless controller for the Switch.
For more on Nintendo Switch Online check out our Switch Online guide for complete features, list of games, and pricing.