Nintendo has been very active with the Nintendo Switch Online + Expansion Pack retro libraries lately. Although it varies which retro library gets updated, Nintendo’s schedule with new additions has reached a point where it is guaranteed to see at least one retro game added a month.
Well, Nintendo has announced this month’s additions. This time, the additions are exclusively for retro libraries that do not require the Expansion Pack. For the NES library, Mystery Tower is now available. The SNES library is getting Harvest Moon. As for the Game Boy library, Nintendo has added Kirby Tilt ‘n’ Tumble and Blaster Master: Enemy Below. Nintendo’s announcement tweet is down below.

They seem to be picking up the pace back up with these releases at least. For a while it was every other months and only like two games.
I still own the cartridge of Tilt and tumble, sadly, it no longer works, so this is perfect!