Nothing to do with the super-strength booze or animated puppets, Thunderbird Spirit is in fact a Native American-themed slot from Genesis Gaming. Played using a 5 reel, 4 row, 100 payline game engine, it comes with a free spins feature with frozen wilds. Play from between £1 and £1,000 per spin.

The design in Thunderbird Spirit is a little unusual – the symbols have the look of fossils about them. Joining the lower value A to 9 playing cards are a quartet of animal spirit symbols. The fish and tortoise offer payouts of up to 5 times your total stake followed by the bison which offers up to 7.5 times your bet. The most rewarding symbol is the snake – land 3, 4 or 5 of these on 1 of the game’s 100 paylines and you’ll win 0.5, 5 or 10 times your bet.

The Native American feathers are the wild symbol, replacing everything apart from the scatter. The spirit bird is the scatter. Land 3, 4 or 5 of these anywhere on the reels on the same spin and you’ll trigger the Locked Wild Free Spin feature.

Once triggered, you’ll be awarded 10 free spins. Every time a wild lands, it will be locked in position for the remainder of your free spins. Unfortunately, it’s not possible to trigger any extra free spins here.

Thunderbird Spirit is a simple game both in terms of how it looks and how it plays – you won’t see visuals like these in many slots. The drum heavy backing track has a rhythmical feel and works rather well to complement the theme.

The bonus feature is a pretty standard offering. The allocation of 10 free spins isn’t especially large but the presence of the locked wilds give it some potential. We triggered it at regular intervals and enjoyed wins in the region of 30-40 times our stake most of the time. We’d put the variance in the medium range.

The features aren’t particularly innovative but the unusual design and locked wilds make Thunderbird Spirit worth a closer look. If you like the theme, Thunderkick’s Turning Totems is recommended.