Casio was on a roll with their baseball series, producing three calculator styles to present the game.
The BB-101 was the third example (following the BB-9 and BB-10). It’s almost identical to the BB-10 other than some changes to the graphics on the case and LCD, and some different colouring.
It is definitely kid-friendly, although the BB-10 was equally so.
Personally, I wonder if Casio was considering moving into coloured LCDs (like Nintendo tried with their Tabletop and Panorama series of Game and Watches) and were feeling their way with this version.
As you would expect, gameplay is exactly the same as the BB-10, and after a few games to get the hang of things, you should be making your way comfortably toward a 9-inning stretch.
There are two other calculator games that used this case layout – the BG-20 (boxing) and MG-200 (turbo drive); plus, of course, the BB-10. Unusually, Casio did a non-calculator version of the other games of this era – SG-11 (soccer), PG-100 (pachinko) and CG-88 (othello/reversi) – perhaps thinking they would sell better as game-only handhelds.
Definitely more of a game with a calculator function than the other way around, Baseball remains one of the most playable Casio calculator games.
The BB-101 is very rare – don’t expect to find more than a couple every few years on eBay.