[Guest reviewer Colin Brown of Backlog Journey looks at each title in Indie Royale's Spring Bundle, available now. First up is Unstoppable Gorg, developed by Futuremark Games Studio, available on Windows, Mac, Steam, Desura, DRM Free.]

This time around the Indie Royale brings us another tower defence, which is great because I just love them and also great because it gives me another chance to ruminate on the game design of tower defences. To revisit an old favourite discussion topic, I mentioned in my rundown of both Defense Grid and Sol Survivor that tower defences usually fall in one of two design directions. You have the clever genre fusing entries which combine tower defence with other game styles a la Sanctum, Orcs Must Die and the Busker made (and utterly fantastic) Pakkuman Defense.

Then you have more straight-laced defence games like the aforementioned Defense Grid, which tend to concentrate on providing the best possible "traditional" tower defence through lots of polish and perfecting of the usual formula. Of course, my little pet theory can be utterly proven wrong by games like Unstoppable Gorg, which manage to take the winning traditional formula and adds completely unique game mechanics without simply resorting to a genre mash-up.

Unstoppable Gorg is a retro throwback, but not in the way you think. Instead of being presented as a throwback to retro gaming, the team at Futuremark have crafted a loving homage to the retro future world of 1950s cheesy sci-fi movies. You are Captain Atom, Earth's premier space explorer and the last hope of stopping the presumably unstoppable Gorg invasion. It's rare for me to call out the cut-scenes as a highlight of a game, but in this case it is both necessary and well deserved. The small snippets of newsreel footage recorded by the developers offer up every bad B movie trope they can think of including UFOs with visible strings holding them up, robots constructed out of cardboard and tinfoil, a brilliant shot of a prop planet exploding, an announcer straight out of 1940s radio and plenty of stock footage. If you're a fan of watching hilariously old and cheesy B movies a la Plan 9 From Outer Space, or you're just a complete Mystery Science Theatre freak like I am, the cutscenes alone are worth checking out.

Luckily the gameplay is no slouch either, presenting a great take on tower defence that puts a unique spin (gag) on things. The basic structure is class tower defence, with the usual gamut of towers of varying effectiveness and utility. The unique element is the way both your towers and your enemies have a fair amount of flexibility. The field is divided up into several orbital paths, with built in spots for towers. By grabbing one of these paths, you can spin all of the satellites in the same orbit around the circle, allowing you to reposition your towers at will. Similarly, the projected path of the enemy may change, or occasionally multiple paths will appear, so you need to orient your towers to the best possible defence plans on the fly.

It seems simple, but that one new element is a fantastic addition that changes up the formula drastically without reinventing it. The spinning towers mechanic is a unique and interesting gameplay aspect that, to my knowledge, has never really been used before. It solves the common problem of lack of player interaction that most tower defence games suffer from, and it does so without transposing the gameplay to a different genre so it retains the very classic tower defence gameplay. Unstoppable Gorg is a game that hits all of the traditional tower defence check marks, but still manages to make it a fresh experience for vets of the genre.

All of this, plus those retro cutscenes that are just really outstanding. If you like sci-fi cheese, tower defence games, or both, you really owe it to yourself to check this game out.

[Unstoppable Gorg and 5 more titles are available now in the Spring Bundle on the IndieGames co-created site Indie Royale.]