Gates of Camelot Slot by Playtech

Most of the action waits for the free games, and that's worth saying up front. The base round gives you a Mystery symbol that lands, opens, and reveals one random paytable symbol across every mystery position at once. When it copies a knight or a crown, a full board of matches can drop in a single spin. When it copies a card royal, you shrug. Hit or miss, honestly. The Expanding Wild Knight works alongside it, an armoured figure that shows up on reels 2, 3 and 4 and stretches to cover the whole reel, standing in for everything except the Scatter and the Mystery symbols.

The Scatters open the round that actually matters. A Symbol Upgrade Track runs beside the reels, and every Expanding Wild Knight you land turns the next symbol on that track into a Mystery symbol and adds one extra free game. From then on, any Mystery that reveals pulls from whatever symbols are still left on the track. And the lowest payers drop off first, so the longer the round runs, the more those reveals skew toward knights, crowns and the ruby chalice instead of jacks and queens. Retriggers stack more spins on top. Once the track has been picked clean and a Mystery fills the board with a premium, wins push toward 7,050x total bet.

The reels sit against a grey stone castle wall topped with crenellations, purple-blue mountains and a hazy dusk sky behind it. Iron-studded wooden portcullis gates front the reels, and here's the odd part: those gates can stay shut over the outer reels while the inner ones play open, so the count of visible positions shifts from spin to spin. Symbols are Arthurian loot, an armoured knight, a jewelled crown, a ruby chalice, an emerald ring and a gold shield, with cut-gem card royals underneath, all leaning hard on the medieval castle-siege look. There's also a plain Wild that subs for everything but the Scatter, no frills attached.