The term Neo ("new" in Greek) was used both in Japanese and English releases to emphasize a new generation of the Pokémon TCG.
The English title, Genesis, is one of two Biblical references in the TCG. The other one is of Neo Revelation. Genesis and Revelation are the first and last books of the Bible, respectively. The name Genesis refers to this being the set to include the first of the Generation II Pokémon found in Pokémon Gold and Silver.
Along with new Pokémon came two new card types; Darkness and Metal. There was also the addition of baby Pokémon and Pokémon Tools, which were Trainer Card items that could be permanently attached to Pokémon in play - referring to Generation II's new feature that allowed Trainers to equip their Pokémon with held items.
A nine-card promo set was released in Japan before Neo 1 was released, featuring the Johto starter Pokémon and their evolutions. For the English release, Wizards of the Coast added the 9 promo cards and the six basic Energy cards to the set, increasing it to 111 cards.
One art change in this set was the Trainer Card Moo-Moo Milk. The Japanese version depicts a Sentret suckling at a Miltank's udder, and was considered inappropriate for children for its English release.
Taking the term Neo literally, the card layout also changed slightly, with updated stat, evolution and weakness/resistance graphics and the use of smaller black HP text (similar to that of Japanese cards) instead of red text.
Some collectors mistook the expansion's double star symbol as an indication of high rarity. The same mistake was also made on the Darkness-type Pokémon, whose rarity symbols were white (white stars in Japanese sets indicating super rarity).