Megaways is a slot engine, licensed from Big Time Gaming, that changes how many symbols appear on each reel every spin — producing a variable and often enormous number of ways to win.
The core mechanic
Instead of fixed paylines, each of the (usually six) reels can show a different number of symbols per spin. Wins are formed by matching symbols on adjacent reels from the left, and the total "ways" can reach 117,649 or more.
Common companion features
Most Megaways titles pair the engine with cascading reels, so winning symbols disappear and new ones drop in, and with increasing multipliers during free spins.
Volatility
Megaways slots are typically high volatility. The huge win potential comes with longer gaps between meaningful payouts, so balance swings can be sharp.
What to check
Look at the RTP and the advertised maximum win, and be aware that the massive "ways" figure describes possibilities, not likelihood. Set a budget suited to a high-variance game before you play.