Every scarab is a claim on one reel
No scarab in this game pays until a Collect lands on reel 5, whether in the base game, in free spins or in the final respin that settles the bonus pot. The game sets that reel's Collect density three different ways: 2 stops in 78 in the base game, 10 in 79 during free spins and 3 in 69 for the finale. My reading of John Hunter and the Tomb of the Scarab Queen comes down to the gap between the last two. The round builds its pot on the most generous reel in the game and settles it on one with about a third of that density, so the scarab mechanic's best idea is paid out at its meanest moment. That is why I think a game with this much range belongs at 6.3.
I see a plain family resemblance. In Big Bass Bonanza and Floating Dragon, fish carry cash values and a collecting Wild pays them during free spins, and Big Bass Splash uses the same pairing. This game pushes that bargain in two directions. The collector is not a Wild but a symbol of its own, pinned to reel 5, and it works in the base game as well as the bonus. It also comes in five types, each paying the scarabs a different way. I count that a real extension of the format rather than a reskin, and its cost shows from the first spin: scarabs land on reels 1 to 4 far more often than reel 5 answers them.
The base game is a line game wearing scarabs
Reel 5 shows three symbols, so at the 96.50% setting its two Collect stops can put a Collect in view on at most six of its 78 positions. I make that one base spin in thirteen at best, and a Collect in view still pays nothing unless a scarab is on screen with it. Set against a base-game hit rate of 39.9%, at least 32 of those points belong to spins with no Collect showing. At least four winning base spins in five, then, are paid by the lines and the Scatter alone.
I do not find a paytable built to carry that load. Three of a kind pays 0.2x the total bet on every symbol except John Hunter, who pays 0.4x, so most three-of-a-kind wins return a fifth of the stake. Five of a kind pays 4x to 7x for seven of the eight line symbols. John Hunter's 32x is the one line pay with weight, and even a screen of John Hunters paying on all 25 lines would stop at 800x, under 8% of the 10,500x cap. A single 35x scarab under a plain Collect outpays five John Hunters on a line. The base game's frequent wins are small, and its large ones wait on a reel that shows a Collect once in thirteen spins at most.
The five Collects differ in kind, not only in size
I rate the Collect family the best thing here, because it is not one idea at five sizes. Extra Credit adds its value to every scarab, so it rewards a crowded screen. The Multiplier multiplies each value, so it rewards big scarabs. On twelve 1x scarabs the top Extra Credit pays 132x and beats a 10x Multiplier at 120x; on a lone 35x scarab a 2x Multiplier pays 70x and beats that same Extra Credit at 45x. Expanding Collect fills each reel holding a scarab with fresh scarabs, so one scarab on each of reels 1 to 4 becomes a full screen of twelve. Respin Collect holds the scarabs in place and gives the screen one more spin to add to them.
Scale is a different matter. With one Collect on a full screen of 35x scarabs, the plain, Expanding and Respin Collects top out at 420x and the best Extra Credit at 540x. The Multiplier takes that same screen to 840x at 2x, 4,200x at 10x and 10,500x at 25x, which is the maximum win to the unit. On a single spin the cap therefore needs the top rung of one Collect type under twelve scarabs all at the top value, and the rung below it reaches 40% of the cap. I read the figure as honest arithmetic rather than a padded number, and also as one exact screen. The Multiplier Collect is what gives this game a top end at all: with any other single Collect, a perfect screen pays 540x at most.
The pot is the best idea and the worst-priced one
Free spins repair the base game's problem and then bring it back at the worst moment. The round's reel 5 has 10 Collect stops in 79, about five times the base share, so a Collect can be in view on up to 30 of its 79 positions, just under two spins in five. Scarabs get paid through the round far more often than in the base game. Every scarab that lands also banks its face value into the pot whether a Collect paid it or not, so each one is a claim on two payments: the Collect on its own spin and the pot at the end.
The finale then settles that pot on a reel with 3 Collect stops in 69, about a third of the density the round has just used, and it shows a Collect on roughly one respin in eight. Roughly seven pots in eight are forfeited, and by my arithmetic that values a pot under a plain Collect at about an eighth of its face. The finale reel is kinder than the base reel, 3 in 69 against 2 in 78, but a base spin risks that spin's scarabs while the finale risks every scarab of the round on a single spin of reel 5.
Retriggers sharpen this rather than soften it. Three Scatters on reels 2, 3 and 4 add 8 spins, and each extra spin banks more face value into the pot, but the finale reel does not change, so a longer round raises the stake on the same one-in-eight draw. The pot also banks face values only, so a spin under a 25x Multiplier Collect adds its raw scarab values to the pot rather than its multiplied total. I take the round's dependable value to be the spin-by-spin collect. The pot is a lottery ticket stapled to it, and the round is built around that ticket.
The Multiplier is the reason to play it, not the pot
I would point this game at a player who wants the scarab draw on every spin and accepts that the base game is a slow line game between Collects. Medium volatility at 3 out of 5 fits that shape: frequent small line wins, occasional scarab payouts, and a top end that rests almost entirely on the Multiplier Collect. Taken as an extra on top of free spins, the pot is harmless. Taken as the reason to chase free spins, it disappoints roughly seven times in eight.
A player who wants line wins to do real work should look elsewhere, and so should one who wants a bonus whose headline feature usually pays. For the collect idea in a plainer form, Big Bass Bonanza and Floating Dragon pay their fish when a collecting Wild lands with them in free spins.
I would check the setting too. At 96.50% the house edge is 3.5%, and at 95.50% it is 4.5%, about 29% more expected cost per unit staked. Many UK casinos run the lower setting, and the rules screen shows the one in use. For me the 6.3 rests on that balance: a collect mechanic with real range, a paytable too thin to hold up the spins between Collects, and a pot priced against the player.