To answer that, there's a number of different aspects that are worth discussing: non-linearity, challenge, and reward structures. Let's dive in.
The first question is how linear is the game? At the far non-linear side of the spectrum are games with a big open world where you can really go anywhere in any order you want. The recent NES homebrew game Lizard by Brad Smith is a good example of this, as is Super Pitfall. There's a big giant world, and it's yours to explore. You can really do things in just about any order you want.
|You can go any way you want in Super Pitfall, but mostly you just die. A lot.|
Then there are games that have a little more linearity to them: the original Metroid is a good example. You can't really progress until you find the missiles and bombs. But when it comes down to it, you can go kill Ridley or Kraid in either order, without ever finding a number of the other powerups. There may be a recommended order to do things, but you're not always doing everything in the same order. (The original Legend of Zelda was very similar in it's non-linearity. There was an order to the dungeons, and some of them required items from other dungeons. But there's not much preventing you from doing some of them out of order(and we did so when we were first exploring the game as kids....if you got stuck on level 6, you went on to try level 7 instead).
Next up are games that are slightly more linear, like Super Metroid. Advanced players know how to exploit the game and can do things out of order, but the average player will end up doing things in mostly the same order every time. Sure, there's plenty to explore, and plenty of secret passages that you may or may not find. But the general order ("find this powerup to open the way to the next section. Find another and then you can go back through that other section") is generally the same for each player. (assuming they aren't purposely going back and trying to break the game sequence).
|Despite the awesome Metroidvania-style map, Circle of the Moon was a huge disappointment to me. Each colored section was a distinct "level" that you had to play through in order.|
At the far linear end of the Metroidvania genre are games like Castlevania: Circle of the Moon. Although it's one big world, it's divided into clear level-like areas. You beat the boss of the first to get an item that lets you explore the next. Beat that next level, and you get rewarded with the power that lets you explore the 3rd section. And so forth. These are the least interesting to me: although they pretend to be big contiguous-world metroidvanias, they're really not much different than a linear level-based game.
Where does Halcyon fit into this spectrum? I'm attempting to place it somewhere between Metroid and Super Metroid. I'd like the player to have a little bit more freedom in the order of things than Super Metroid, but I found Metroid to be a little too painful in terms of a beginning player not having any idea of where to go. A few parts of Halcyon will require you to go get powerup X right now to continue, but there will be other parts of the game where you can decide which way you want to go, with a number of different areas to explore and routes to take.
As a side tangent -- the world in Halcyon is a euclidean contiguous world. There are no warps between worlds or front/back (like Goonies 2) or weird non-euclidean layouts like Blaster Master. It (like Metroid) is just one large mappable world.
|Robo-Ninja -- possibly the world's first tap-to-jump metroidvania?|
When I'm talking about a difficulty spectrum here, I'm talking not about how big or confusing the world is, but how difficult the enemies, obstacles, and other "platformer skill" elements are. The original Metroid was a pretty tough game, particularly at the beginning when you didn't have many energy tanks). Lizard is HARD -- you die A LOT. Blaster Master had a weird difficulty curve -- some levels were really easy, but some levels (and bosses) made you want to punch the screen.
|The game was fun and easy-going until you had to fight THIS GUY.|
Super Metroid, on the other hand, wasn't a very hard game. There were a couple parts that were tricky, but you really didn't die all that much. The fun of the game was exploring and figuring out where to go, and looking for secrets. The enemies were mostly just there to keep you on your toes.
Symphony of the Night was also like that. Other than that one boss (I don't remember his name, but I'm sure if you played it, you know who I mean), it was a fairly easy game, mechanically. The joy of the game wasn't in the finesse of fighting and jumping.
Unlike Robo-Ninja, this time I'm going easy. Halcyon is (hopefully) going to be more like Super Metroid or Symphony of the Night in this regard. If I can get the difficulty set the way I want, you might die a couple times, just enough to keep you interested and careful. But the combat isn't supposed to be hard. Anybody with moderate video game skill should be able to take their time and explore and enjoy the game.
One of the things that I want from Halcyon is for exploration to feel rewarding. Super Pitfall had a giant world with lots of areas to explore, but it was just a vast mostly-empty world. There was nothing that made you feel rewarded when you went this way vs that way. You'd explore a route and die, without having found anything interesting. You'd try a different route and die. You never seemed to make any sort of progress.
Lizard also had a fairly brutal reward system (in my opinion). There were coins scattered around the world, but you had no idea what they were for, and you'd lose them if you died. If you explored a lot, you could find a new power (a new lizard costume), but you didn't get to keep it. Even defeating a boss just mostly felt confusing to me. These were all purposeful design decisions that Brad made (as opposed to just poorly-designed flaws), but playing it helped me figure out what sort of feeling of reward I wanted to put into Halcyon.
|This screenshot from Lizard sums up how I felt most of the time.|
First, I wanted a map screen that would be permanently revealed as you explored. (Like Super Metroid, Symphony of the Night, or many other newer games). With a revealed map, you always feel like you're making progress. Even if you get fairly lost, and don't discover where to go, your adventurous route is marked on your map. There's some internal feeling of reward in uncovering the map. You did something permanent. You got here once and you know how to get here again.
Second, I wanted a lot of powerups scattered throughout the world. Heart containers in Zelda and missile packs in Metroid were great -- they could distribute them freely all over the place, giving you lots of minor rewards throughout the game. I love Super Metroid's method of putting a minor reward behind some secret passage. The real thrill was finding the secret passage, but they gave you a permanent upgrade as a reward once you found it. To make this happen, I have a number of types of powerups in Halcyon, so that I can hand them out like candy. There are a few major ability powerups (which are the keys to unlocking content and progressing), but there are also new alternate weapons, max health increases, weapon power increases, energy increases, etc. If it was ONLY health increases, I think they would quickly become boring and lose their sense of reward. So my goal is to have all sorts of types of things to find to keep it feeling rewarding.
|A tiny sliver of Halcyon's minimap|
Hopefully my describing where Halcyon fits in along each axis will help provide a better picture of "just what is this game all about, anyway?" But just a few more bullet points might be helpful:
- There's a little bit of story/plot, but not much. If all goes to plan, and
we can get the details ironed out, there will be an opening story sequence, a tiny bit of plot along the way, and and ending story. But this won't be a story-driven game. You won't be talking to lots of people, getting clues in towns, or interacting with a lot of characters and dialog.
- Like Blaster Master, there will be a dynamic of getting in and out of your
vehicle to explore different areas that are better handled on foot or in-vehicle. Unlike Blaster Master, there are no overhead sequences. The world is one single contiguous side-scrolling map.
- There will be secret passages and hidden items. More Metroid than Blaster
master in this regard. Some will be pretty obvious. Others might be rather difficult to find. (dare I say obtuse?) My goal (if I pull it off well, which I may not) is that all of the secret passages necessary to win the game will be fairly intuitive to find, while many of the optional routes or powerups will be better hidden.
If you have any questions, I'd love to hear from you! Pester me on Twitter or email at email@example.com.