Originals are games developed by the crypto casino itself, not bought in from third-party studios. The typical selection is crash, dice, plinko, mines, limbo and roulette-like variants.
Three things that set them apart
A higher RTP. With no intermediary the house edge is usually 1–4% — a higher RTP than on most slots. Dice and plinko are the cheapest games on the market at all.
Provably fair. Only the results of originals games can be verified yourself. Third-party studio slots and live tables use ordinary certified RNG and cannot be checked that way.
Maths that differs by house. A game with the same name is not the same game at different houses. The multiplier table, the risk levels and the RTP can differ, because each house writes its own version. No comparison site can promise that your house's numbers are the same as elsewhere — check them on the game's info sheet.
The wagering trap
Precisely because of the high RTP, originals games are almost always excluded from bonus wagering or count at a reduced weighting. If you plan to clear a bonus, a slot is mostly the only full-weighting choice.
Where to look
Crash, plinko and dice each have their own list; the provably fair houses are the ones where the check genuinely works.