Alien Invaders - the Rules, Restated
Verdict first: the strangest board on this shelf and the best-documented one. Reels of changing height, a marked bottom row that decides every win, and an RTP line printed where every player can read it. The 31 info screens of the build we logged are restated below, converted to multiples of the total bet. The demo runs right here - test each rule the moment it sounds odd, because several will.
The numbers this build prints
Page 5 of 8 in the info screens carries the line most games hide: the theoretical RTP is 96.50%. The build goes further and prices its own extras as well, 96.51% with the Ante Bet, 96.49% for the Free Spins buy, 96.51% for the Super buy. The maximum win is printed too, 5,000x the bet, with a hard stop: when a Free Spins round reaches the cap, it ends immediately and pays the cap. Volatility is flagged at five lightning bolts out of five. Stakes run from a printed minimum of 0.20 to a printed maximum of 300.00. This is what full disclosure looks like, and it costs the studio nothing.
The marked row, and what a win is
Five reels land 3, 4 or 5 symbols each, at random. Only the bottom row is marked. Three or more matching symbols in that row start a win, the reels holding them switch to active, and every copy of the winning symbol on the active reels joins the combination. The paytable prices each symbol in the combination, not each line.
| Symbol | Per symbol in a win |
|---|---|
| Fire monster | 1x |
| Ice monster | 0.5x |
| Horned monster | 0.25x |
| Yellow-green monster | 0.25x |
| A | 0.1x |
| K, Q, J, 10 | 0.05x each |
The Wild pays on its own as well - 0.05x for one, 0.1x for two, 0.15x for three. Small units, deliberately: the game expects long combinations, tumbles and a multiplier to do the arithmetic, not a single line hit.
Tumbles, the counter, and the feature
Winning symbols pay and vanish, the rest fall, new symbols drop from above - the tumble runs until nothing new connects. Every spin starts a win multiplier at 1x, and every 10 symbols destroyed add 1x to it. The Scatter meteor adds its own violence: when it reaches the marked row it explodes with all neighbouring symbols, and the debris pays as combinations. The Wild lands on reel 3 only in the base game, carries a multiplier up to 25x, and works only from the marked row, and a Wild stuck above the row is scenery.
Three or more Scatters across a spin and its tumbles award Free Spins, 7 plus 3 for each Scatter past the third. Inside the round the reels start at 3 symbols and can grow to 5, the Wild appears on reels 2, 3 and 4 with multipliers up to 100x, every Scatter reaching the row adds one spin, and the win multiplier never resets between spins. That last clause is the entire feature. Our pool logged 37 rounds and the best paid 584.65x; the review breaks the distribution down.
Ante and buys, at printed prices
The Ante Bet runs at 25x the base 20x unit - plus 25% per spin for a doubled chance of a natural trigger and more Scatters on the reels, with the buy menu switched off. The Free Spins buy costs 65x the bet. The Super buy costs 400x and starts the round with the win multiplier already at 50x. All three prices print on their buttons, and each carries its own RTP line on page 5. None of the 37 rounds in our pool used any of them.
- Rules restated, not quoted - the eight info pages inside the demo carry the exact wording.
- Paytable shown at the 2.00 reference stake, converted to per-symbol multiples. The screen shows cash at your stake.
- Scatter and feature frequencies - the build prints prices, not odds. Unverified by us beyond the 37 logged rounds.
- Reel-growth odds inside Free Spins - not stated anywhere. Treat the 3-to-5 range as the only fact.
Quick answers
What RTP does Alien Invaders actually print in its rules?
96.50% theoretical, on page 5 of 8 - plus separate lines for the Ante Bet at 96.51%, the Free Spins buy at 96.49% and the Super buy at 96.51%. The figure that binds is the one in the build you open.
How do free spins trigger in Alien Invaders?
Three or more Scatter meteors across one spin and its tumbles - 7 spins, plus 3 for each Scatter past the third. During the round every Scatter that reaches the marked row adds one more spin.
What do the Alien Invaders buys cost?
65x the bet for standard Free Spins, 400x for the Super version that starts the multiplier at 50x, and the Ante Bet at plus 25% per spin. Every price prints on its button before you commit.
Is the free demo the same game as the paid version?
Same rules screens, same printed RTP, virtual balance - the build on this page is the one our sessions logged. Free play still means 18+, and the full session record sits behind the review.
Verified against
Session ALIN-20260729-01 - 2,798 spins of the 6,196-spin pool at a flat 2.00, July 2026, checkpoint discipline throughout. The session tables, screenshots and the score live in the Alien Invaders review. The launch build is on the demo shelf, and the protocol is on the methodology page. The tumble mechanic itself is written up on the cascade slots page - four other tumbling builds lined up next to it. What this page did not verify - reel-growth odds and Scatter frequency. Both go on the list for the next build. 18+ applies to every mode of this game.
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