Drawing inspiration from the genre

The other day I spent some time "researching" (ah, the things I go through for science...) to see what other games have to offer above and beyond the typical standards of the genre.

I played through an interesting flash game called Arzea, which was made by Arkeus for Ludum Dare 22, a 48 hour game design competition. What really stood out to me in this game was the sheer simplicity of it, and yet it felt like it had quite a bit of depth. In addition to locked areas requiring keys, game areas were gated by having higher and higher walls, which required collecting max jump height increasing power-ups. The fact that the player character becomes significantly stronger throughout the game, in addition to the way save points completely restore health, made the game easy, but given the rapid development, it's certainly forgivable.

How much more tutorial could you possibly need?

Another game that really drew me in was Treasure Adventure Game by Robit Studios. There were several things that stood out about this game, but I would have to say my favorite would probably be the hats. In the game, your character can obtain several different hats, each of which serves a very specific purpose. For example, wearing the blue hat will trick flashlight-wielding robots into thinking you're the janitor at the company building, so they won't sound the alarm if you walk into their path. Overall, this game was unique for a lot of reasons, and it's definitely worth a look if you haven't played it yet.

The Magic Bottle from this game was a huge step into unfamiliar territory that really paid off. Many of the puzzles in the game are solvable by using a different function of the bottle, whether it's capturing fire to spew at thorns blocking your path, or capturing wind to make a propeller work, and several other uses. At one point you could even capture hallucinogenic smoke created by burning mushrooms to make invisible blocks appear while distorting vision of the world around you.

Blue hat makes this area a snap. Without it, not so much...

I could probably go for pages and pages about Metroid games like Metroid, Super Metroid, Metroid Prime, and Castlevania titles such as Symphony of the Night, Dawn of Sorrow, Portrait of Ruin, and so on, but it's almost too obvious to talk about Metroid or Castlevania games in the context of the Metroidvania genre (see how that works?) - The most important thing I take away from looking to these examples is that each of these games expanded the style in different ways, and it's incredibly rare to see stagnant gameplay in these series. The core concept and style stay the same, but so many gameplay options change in so many drastic ways.

This part of the Metroid wiki page pretty well sums everything up:

Common gameplay elements

The Metroid series contains gameplay elements from shooter, platformer, and adventure games. The series is notable for its non-linear progression and solitary exploration format where the player only controls Samus Aran, with few or no other characters to interact with. The series has been a 2D side-scroller in all its incarnations until the Metroid Prime series changed the perspective to a first-person perspective, leading to a new first-person shooter element. The player gains items and power-ups for Samus's cybernetic suit by defeating alien creatures through real-time combat with her arm cannon, which enables further exploration. A recurring upgrade is the Morph Ball, which allows Samus to curl into a ball, roll into tight places and plant bombs.

The original Metroid was influenced by two other major Nintendo franchises: Mario, from which it borrowed extensive areas of platform jumping, and The Legend of Zelda, from which it borrowed non-linear exploration. The game differed in its atmosphere of solitude and foreboding. Metroid was also one of the first video games to feature an exploration to the left as well as the right, and backtracking to already explored areas to search for secret items and paths.

That's right, you could move left and right. 1986 was a year for radical new thinking.