Sky Force is a series of Shoot 'em Up games by Polish developer Infinite Dreams Inc., originally released mobile phones in 2004. It is influenced by vertical arcade shooters such as 1942 and Raiden.
Both games start off with you with control of a rather weak plane that can only slowly fire one shot at a time, but it can be gradually upgraded with stars you collect in the levels for much greater firepower, both by increasing the power of your main weapon and unlocking new ones. This in turn enables you to complete later levels and higher difficulties, which reward more stars to upgrade with, and so on. There are also temporary power-ups to be found in every level, including weapon upgrades which can increase your fire rate up to ten times, and the shield, laser, and megabomb power-ups which can be used on demand for temporary invulnerability, a piercing attack, and a Smart Bomb, respectively. Other unlockables include parts for new planes with special abilities, technicians that can provide their own unique advantages, and cards, which can provide various permanent or temporary boosts.
The series so far:
- Sky Force (2004) — The original game. Originally released for mobile platforms such as Pocket PC, Symbian, and webOS, and later Android and iOS.
- Sky Force 2014 (2014) — The remake of the original game. Originally released for Android and iOS as a free-to-play game.
- Sky Force Anniversary (2015) — An Updated Re-release of the 2014 remake. Originally released for Steam as a paid game, and later PlayStation 3, PlayStation 4, PlayStation Vita, Xbox One, Wii U, and Nintendo Switch.
- Sky Force Reloaded (2006) — The sequel. Also released for Pocket PC, Symbian, and webOS, and later Android, iOS, and PlayStation Portable.
- Sky Force Reloaded (2016) — The remake of the sequel. Originally released for Android and iOS as a free-to-play game, and later Steam, PlayStation 4, Xbox One, and Nintendo Switch as a paid game.
The series contains examples of:
- Beehive Barrier: The energy shield power-up, which provides temporary invulnerability to almost everything on use.
- Bullet Hell: ...ish. While not at the level of stuff like DonPachi, with the majority of the game being a more traditional top-down shooter in the style of 194x or Raiden, some areas definitely count. The fixed emplacements that fire patterns of bullets you have to fly through are prime culprits, as well as the guided-missile helicopters whose munitions you'll have to evade. And of course every boss has a bullet pattern that needs to be learned and avoided.
- Level 5 forces you into avoiding bullet patterns for the duration.
- Charged Attack: One of the permanent cards unlocks this ability, allowing you to stop firing temporarily to build up a massive burst. It's a bit dangerous though, as charging for too long will cause the plane to self-destruct.
- Daddy's Little Villain: The Big Bad of Reloaded, Scarlett Mantis, is the daughter of General Mantis, the main villain of the original game. She attacks with her own giant tank, the Scarlet Heart.
- Early Game Hell: At the start of the game, your plane is incredibly weak, making even the first level a relative challenge. It isn't until you've unlocked all your weapons and upgraded the main cannon some that things get easier.
- Early-Installment Weirdness: The original 2004 release uses sprites exclusively. All subsequent games utilize polygons to some degree.
- Equipment Upgrade: Unusually for a shoot-em-up game, Sky Force utilizes an upgrade system. Finishing levels and completing objectives gives the player resources to upgrade their firepower, health, and unlock new weapons.
- Final Boss Preview: The end of the intro level in both games has you encounter the Final Boss early, who's impossible to defeat at this point.
- Macross Missile Massacre: The Octopus plane replaces your missile weapon with a swarm of mini rockets. While each does less damage than a standard missile, they're generally much more useful as they can attack many enemies at once, rather than having all that firepower go to waste to take down a single enemy plane. On the PC version, the Charged Attack takes this up to eleven, firing loads of rockets rather than bullets.
- One-Hit Polykill: The wing cannons, in addition to dealing higher damage per shot than the main cannon, can pierce enemies, making them very effective against lines of enemy planes. The laser power-up can also do this.
- Painfully Slow Projectile: the only reason the player is able to survive at all is that most attacks (with a few notable exceptions...) can be avoided relatively easily, the danger coming more from the sheer amount of them at the same time than from their ability to effectively reach the player. However, this can sometimes backfire - some enemies' projectiles are so slow that you're liable to dodge them, forget they're still on the screen, and promptly fly back into them while retreating from something else.
- Sequential Boss: Most of the bosses have multiple phases of combat as you destroy their weapons and they start using new ones, before you're finally able to put them down for good.
- Smart Bomb: The Mega Bomb. On use, it destroys all nearby projectiles and does major damage to enemies. It can be upgraded to increase its radius and damage.
- A Taste of Power: Both games starts you off by throwing into combat with a well upgraded plane to serve as a tutorial, but it's inevitably destroyed by the end of the level no matter how well you do. You're then given a replacement plane that has to be upgraded from the ground up.
- True Final Boss: Arachnotron in the original game and The Omega in Reloaded, AI controlled aircraft with numerous weapon systems including a massive laser attack. They appear only after the defeat of the respective game's Big Bad and credit roll.
- The Warlord: General Mantis, the Big Bad of the original game, commands the enemy forces in his massive plane, the Nasty Owl.
