Gates of Olympus 2500 uses cascades and multiplier symbols in both the base game and free spins, but the way multipliers work changes once the bonus starts.
In the base game, a win forms when at least 8 matching symbols appear anywhere on the 6x5 grid. The winning symbols then disappear and new ones fall into the empty spaces. If the new symbols create another win, the same paid spin continues through another cascade.
Multiplier symbols can appear during these cascades with values from 2x to 2,500x. If more than one contributes to the winning sequence, their values are added together. For example, a 10x and a 25x multiplier produce 35x in total. In the base game, the accumulated multiplier is limited to the current paid spin and its cascades, then resets before the next paid spin.
Free spins begin when 4 or more scatters land, giving you 15 spins. Before the round starts, the bonus wheel chooses one of four versions: free spins 1, free spins 2, super free spins 1 or super free spins 2.

In free spins 1, only multipliers connected to a win are added to the pot. In free spins 2, every landed multiplier counts, even if that spin does not produce a win. The super versions follow the same two rules, but every multiplier starts at 10x or higher. Unlike in the base game, the accumulated multiplier carries over from one free spin to the next.
You can also extend the bonus. Landing 3 scatters during free spins adds 5 more spins, while the multiplier already collected stays active.
Wilds, Bonus Symbols and Payouts
There is no standard wild symbol. Scatters have two jobs: 4 or more trigger free spins, and they also pay 3x for 4, 5x for 5 and 100x for 6 or more. Regular symbols form a win when at least 8 matching symbols land anywhere on the grid.