Space is hot again in the second decade of the 21st century. It has been a little over fifty years since Neil Armstrong muttered the unforgettable words: “That’s one small step for man… one giant leap for mankind”, as he took his first steps on the lunar surface. Many expected this to be the beginning of a new and exciting phase of space exploration. Still, the reality was anything but – the next 50 years saw little advancement until Elon Musk’s SpaceX appeared on the scene. Back to Push Gaming’s new Super Stacks slot, though, which has a 5,000x maximum win and a 96.23% RTP. I will not even try to discuss the payout mechanics just yet – you’ll find out why soon.
The paytable and help files for this game could fill an entire book, so I can’t hope to cover every single aspect of the game in this review. I’ll try my best; however, let’s start with the instant prize blocks, denoted by coloured “squircles” with diagonal numbers printed on them. These pay between 2x and 50x your current stake, and there is also a “MAX” block that pays an amazing 5,000x … I wonder what the odds of that one landing might be? Then, there’s the Astro Feature, a 32-segment bonus wheel featuring multipliers, instant prizes, and the dreaded collect segments. A flip feature gives you three chances to pick prizes from a 6x6 grid, whilst an Apex feature uses yet another separate grid layout combined with an “enhancement feature” and offers the opportunity to win some truly humongous returns.
This game is as unique as they come, and even the best slot reviewer in the world would struggle to describe every aspect of it concisely. For that reason, I suggest that you fire up our free demo slot of Space Stacks for yourself!
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We talked a little about space in our opening paragraph. However, there is still plenty more to say – I expect we’ll be seeing many more space-themed slots in the next few years because of the development of SpaceX’s Starship and NASA’s Artemis project – if their multi-billion-dollar rocket made of old shuttle parts ever gets off the ground that is, anyway. Star Guardians wasn’t a bad attempt by any means, but we deserve some real Stargate and Star Trek branded slots, don’t you think?
Oh my, we are about to have fun with the paytable too, aren’t we? This game uses ten rows and ten columns, but you need to place a bet on each column to win anything that lands on it. This is a complex setup that can get really expensive if you want to make the biggest prizes worth any real money; take the “MAX” instant prize block, for example, which is worth 5,000x your bet, but if your bet is only a penny, you’ll only be winning €50.00. Interestingly, all of the prize blocks have different RTPs, too – the “MAX” block has a 96.07% RTP, for example, while the lower-paying blocks steadily increase higher RTPs.
Fancy a bit more confusion? You might assume that the “50” instant prize block would pay you 50x your bet, yet the paytable states that its “minimum” payout is 50x, whilst its average payout is 65.026x… and the RTP is 96.13%. The “10” instant prize block has an average payout of 13.706x and a 96.22% RTP. The weirdness continues right the way down the list, and there are even two different prize blocks labelled with a “2”, and these have average payouts of 2.759x (RTP 96.35%) and 2.457x (RTP 96.39%). I know that they say space is hard and everything, but come on, that doesn’t mean that space slots must be hard to understand… does it?
At the start of each spin, you can choose from various casino chips to wager on each of the ten different symbol types. For example, you can bet up to €10.00 on the “MAX” instant prize block, up to €20.00 on the Astro, Flip, and Apex bonus blocks, and then up to €100.00 on each of the lower-paying instant prize blocks. This means that you can bet as low as €0.10 on a round if you wish – although doing so is probably not worth the trouble – or as high as €670.00 per round (!!!) if you want to go max bet on every possible option.
base game & MODIFIERS
Space Stacks slot base game
After you have selected your bets on the initial screen, a ten-by-ten playfield is displayed with each of the symbols that you have bet on shown horizontally across the top of the screen. After this, several drop sequences will commence where blocks fall onto the playfield from the top, filling up each of the ten-high columns. The first column(s) to reach full capacity will award a win.
instant prize blocks
There are seven instant prize columns with payouts ranging between 2x and 50x, or 5,000x for the single “MAX” instant prize block. These are the most common columns that will fill up, whilst the three bonus columns are much less likely to fill up to capacity.
You can think of this setup as being analogous to the odds of hitting scatter symbols in a regular slot, with the exception that there are no “dead spins” in Space Stacks – you will always win something. However, more often than not, it will be less than the wager you have made to play the current round. The feature blocks are much more exciting, so let’s move on to those now.
space stacks slot bonus features
Space Stacks slot bonus feature
There are three feature block columns labelled “ASTRO”, “FLIP”, and “APEX”. The average payouts for these columns are 34.232x, 64.143x, and 299.335x, respectively. The corresponding RTP numbers stated on the paytable are 96.19%, 96.17%, and 96.09%, suggesting that the Astro feature should have superior returns to the Flip feature, whilst the Flip feature should pay more than the Apex feature.
My own results did not tally with the above assumptions; however – whilst RTP is undoubtedly an important factor in determining the value and potential of a feature, it should always be considered as a guideline only. But just what are these features anyway? Let’s find out:
Fill up the ASTRO feature column, and you will soon find yourself looking at the ASTRO wheel – this 32-segment disc contains numerous cash prizes, bet multipliers, and the dreaded “collect” segment. The thing is, the paytable seems to suggest that there is only one collect segment when the truth of the matter is that there are just as many collect segments as there are valuable segments.
So, the ASTRO feature had the highest RTP of the trio, yet playing it turned out to be disappointing. What about the FLIP feature, then?
If you successfully fill the column corresponding to this feature, you will be presented with a 6x6 grid of purple squares. Underneath these purple tiles lurk all kinds of cash prizes and several “rocket” symbols, which are undoubtedly your preferred target when picking squares from this grid. You only get three chances to uncover a prize from underneath a purple tile; however, if you manage to find a rocket, then your remaining picks will not be reduced.
The first time you find a rocket symbol, your current winnings will be multiplied by 2x. Find another rocket, and your multiplier will increase to 5x. You’ll need a miracle to locate all four of the rockets hidden on the grid. Still, if you find the third and fourth rocket symbols, congratulations – your multiplier now increases to 10x or 100x, respectively.
Finally, let’s talk about the APEX feature – this one has the lowest RTP of the three, yet my own experience suggests that this is where the game’s biggest wins can be found. Go figure! The feature begins with an enhancement stage which will boost the value of each of the games’ symbols by either 2x, 3x, 4x, 5x, 6x, 7x, 8x, 10x, 15x, or even 20x.
Next, you will be presented with a new grid format which contains only the six instant prize blocks - yes, I did say six, as the MEGA block is missing from this bonus round for some reason. Talk about a cop out! The feature will progress with several free drops of symbols, and each time a column is filled to the top, you will win its associated prize, multiplied by the value achieved during the enhancement stage.
Once two columns have been successfully filled, the bonus round will switch into a typical three-spin format, where you must land at least one new useful symbol on each drop to avoid losing a life. Lose three lives in a row, and the feature will end. If you are lucky, however, you may manage to fill all six columns e before running out of lives; I achieved this twice during the time I spent testing this game – roughly two hours – suggesting that it isn’t all that hard to achieve.
space stacks slot review final thoughts
What can we say? Online slots do not come much more unique and innovative than this one – trust me, you have never played anything like it! I really enjoyed it myself, so I recommend you search this one out and give it a blast.
My suggested strategy is to place a bet on all ten columns – pick a couple to place some big bets on, then just put something close to the minimum on the rest of the symbols. With your wagers configured, just keep hitting spin until you manage to hit one of the three bonus rounds and see what happens next!
I’m intrigued to see if this game will be successful for Push Gaming – the design and mechanics are entirely new and unique, and who knows, perhaps the developer could turn this system into the next Megaways style licensed slot machine schematic. I guess that only time will tell!