It's not flatland, and it's not the space-time continuum of the 4th dimension, it's 1995 UC3.
A strange number of 147 card base set distributed in 5 card packs, 36 packs per box, probably $2.49 per pack if my memory's right.
There were different designs for AL and NL players with ALers having a giant baseballs and NLers having a giant glove with the player superimposed. Look, the baseballs are flying at you.
Only one rookie in the set: the ubiquitous Hideo Nomo.
There were three insert sets and one parallel set in 1995 UC3.
Clear Shots was a bunch of clear plastic rookies and newcomers, Cyclone Squad had psychedelic spinning wheels on the cards, and In Motion was made of 8 virtual pieces of players flying apart in sections as the card was tilted. The Artist Proof parallel was the staple of the Pinnacle Brands products and the cards were marked with the seal indicating it as such.
The set concept lasted a year. The flying baseballs in the background coming at you in almost 3D (UC3! Get it?) must have not been the sticking, far-reaching concept that they had initially hoped. (Sidenote: In 1997, Upper Deck released a set called UD3, which was not an offspring of this set even though it was next in sequence. I guess the next step would be to release a set called UE3).
This was supposed to be the higher-priced, premium cousin to Sportsflix except there weren't any changing images except on the inserts. The lithographic surface remained, but it didn't have the same fun as tilting the cards to make the players move. Plus, players getting swallowed by giant gloves was a disturbing image for even the most non-squeamish collector. Paying more for essentially the same set without significant changes did not let it thrive. Of course, today, a set with that name could come with 3-D glasses and a 46 inch LCD TV, then you could really see all 3 dimensions of the card. The inserts were both interesting and annoying to look at. I think I bought some packs of this many years after the fact, it was a good buy for $0.99 per pack.