Xexyz

A 1988 video game for the NES developed by Atlus and published by Hudson Soft. Originally released in Japan as Kame no Ongaeshi: Urashima Densetsu ("The Turtle Returns: The Legend of Urashima").

You play as Apollo, a warrior in a white spacesuit with a visor that looks like a duck's bill, as you make your way from island to island in a post-apocalyptic Earth, fighting off bizarre aliens and robots and rescuing a bevy of princesses from their clutches. A variety of special weapons help you on your journey, while aircraft called "cyborg riders" take you from one locale to the next. Along the way, you meet fairies, disembodied heads, friendly frog-ladies, robot shopkeepers, and giant women in hot tubs. The kingdom of Xexyz depends on you!

Needless to say, it's a bit strange.

Tropes used in Xexyz include:

Achilles' Heel: Every boss has a weak spot of some sort.
After the End
American Xexyz Is Hardcore: The game's title screen, and a few character and enemy designs, were changed from the Japanese version to the US version to take on a less whimsical, more sci-fi appearance. The flying saucer Apollo rides to combat each platform-stage boss was originally a flying turtle, and the Gradius-like ship used to finally destroy Goruza's fortress originally had a turtle motif to it. Compare the differences.
Betting Minigame: Subverted in the American version. You bet 20E, and while the Japanese version allows you to win as little as 5E, in the American version the minimum payout is 30E; you always come out ahead.
Big Bad: Garuza, the leader of the aliens.
Boss Rush: One of the secret passwords allows the player to challenge all odd-level bosses in back-to-back battles.
Damsel in Distress: The queens of each island, in addition to fairies trapped by enemies.
Fairy Tale Motifs: Aside from rescuing princesses, the game was apparently inspired by the Japanese fairytale of Taro Urashima, a fisherman who saves a turtle, goes to a magical undersea palace, comes back to find that a hundred years have passed, and suddenly dies of old age. The connection to the fairytale amounts to a preponderance of undersea-themed enemies and a turtle-shaped spaceship you ride near the game's end.
Giant Space Flea From Nowhere: Every dang boss.
Multiple Endings: The Japanese version ended with a simple choice between three endings, one of which is a Bad Ending.
Nintendo Hard: Apollo moves fast, both vertically and laterally, making him difficult to control. Also some bosses can kill you in less than 5 hits, even near the end of the game when your life bar is close to or is already at the max.
No Pronunciation Guide: The American commercial for the game pronounces the title "ZEX-iss", though other variants ("ZEX-eez") may be heard.
Our Monsters Are Weird: Up to and including worms with rocket launchers strapped to them.
Pinball Projectile: The 45B Ball weapon bounces off surfaces and into enemies.
Unexpected Gameplay Change: The levels alternate between Platformer, Metroidvania, and Horizontal Scrolling Shooter.
When All Else Fails Go Right