Journey To The Wealth Slot by PG Soft

Four characters from the Journey to the West mythology - Monk (Tripitaka), Monkey King, Pig, and Sandy - double as both premium pay symbols and the key to the free spins mechanic. Scatters only appear on the three center reels, and you need all three (reels 2, 3, and 4) to trigger 8 free spins. Land just two on reels 2 and 3 without one on reel 4, and you get a single respin instead, with one random character symbol transforming into a Wild for that spin. The respin is a consolation prize, basically.

Free spins are where the game gets its structure. Every Wild that lands during the bonus round gets collected into a progress bar with four thresholds. Hit 3 Wilds collected and all Monk symbols currently on the reels transform into Wilds, plus you get 2 extra spins. At 6, Monkey symbols join the transformation pool alongside Monk. At 9, Pig gets added too. Reach 12 and all four characters convert to Wilds on every spin for the rest of the round, with each milestone adding 2 more spins to work with. So the bonus builds on itself - more Wilds collected means more symbols transforming, which means more Wilds landing, which pushes you toward the next threshold. Whether you actually chain past the first or second milestone depends on how generous the early spins are with Wild placements. The 8,000x advertised max needs a deep run through all four tiers, though simulated results across a billion spins topped out at 1,266x, modest by modern standards.

Base game runs on 30 fixed paylines with no multipliers, no tumble, no buy bonus option. Wilds substitute for everything except the Scatter. The collection mechanic during free spins is the only thing separating this from a completely standard payline slot, and it carries about 41% of the total return. Outside that bonus round, the game plays flat.