Alien Invaders

Pragmatic Play built Alien Invaders around a bottom-row win mechanic rather than paylines running across the whole grid: the reels hold three to five symbols each, but only matches landing along the highlighted bottom row register, after which every reel carrying a winning symbol turns active and every copy of that symbol on those active reels counts toward the payout. Once a win locks in, the involved symbols clear and new ones drop from above, so a single spin can chain through several rounds of tumbles before settling. The alien cast leans toward a friendly, rounded look rather than anything overtly threatening, keeping the presentation light despite the invasion premise.

Paytable symbols run from 10 through Ace as the low end, worth 0.05x to 0.1x per line, up to four alien-themed high symbols paying 0.25x to 1x. A wild lands on the middle reel during the base game, expanding to the middle three reels in free spins, substitutes for everything except the scatter, and pays 0.05x on its own — but it only counts as active once it reaches the bottom row, and it can also carry a random bonus multiplier ranging from x1 to x25 that feeds straight into the win multiplier. That win multiplier itself starts every spin at x1 and climbs by +1 for every ten symbols removed through tumbles or through the scatter's explosion effect, then applies to whatever combination is currently paying.

The scatter symbol can land on any reel, and when it reaches the bottom row it detonates along with every symbol touching it horizontally, vertically, and diagonally, with the cleared symbols counted as a win in their own right. Collecting three or more scatters across a spin awards 7 free spins, plus 3 more for each additional scatter beyond the third. Inside the bonus, reels start at three symbols each but can grow by one per spin on a randomly chosen reel, up to five, and once a reel expands it stays that size for the rest of the round. The win multiplier carries over between free spins instead of resetting, and the wild's random multiplier range extends up to x100 rather than x25, while any scatter reaching the bottom row now adds an extra free spin on top of its explosion.

Buying into the feature costs 65x the stake for the standard version of the bonus, or 400x for a version that starts the win multiplier at x50. The published numbers put return to player at 96.5% by default, with 95.48% and 94.51% as alternate configurations, volatility rated high, a maximum win of 5,000x the stake, and a hit rate of roughly 1 in 2.9 spins across a bet range of 0.20 to 240.