I'm slowly working on my own vaguely Metroid-styled game (2D, not 3D), and so I spend some of my time trying to think up enemy designs. And it's harder than I'd realized! The key thing is, most 2D Metroid enemies are not particularly aggressive; many completely ignore the player (e.g. wallwalkers, or enemies that just fly back and forth, or enemies that just literally sit in place) and the ones that do react tend to move slowly. The most difficult enemies move erratically and/or quickly. So I'm trying to think of movement patterns that result in a similar kind of experience, and it seems like Metroid's stolen all of the good ones. I mean, I want my game to feel like a Metroid game, but I don't want people saying "Oh, and these guys are from the first game, and I recognize those, though they have a new paint job...". In other words, the gameplay should feel new, and for that I need my own enemies. But it's tricky. Here's what I have so far: * I think the basic wall-walker is a common-enough trope that I can re-use it without raising any eyebrows. * I have some thoughts on a combination bat/hawk thing that would hunt by dive-bombing the ground/surface of the water (not hunting the player, mind; just getting in the way, in that respect). * There's this guy who would charge along the ground and maybe do some jumping. * Along the more aggressive side, I do plan to include some stationary turrets. And that's pretty much it. Obviously I don't have enough to populate a game with. I'm not even remotely close. If you have any ideas of your own, I'd love to hear them.

Right, yes, the animals are just being animals, and to a large extent it's your own fault if you get in the way. What I'm trying to do (and not having much success at) is coming up with creatures that would:

* have interesting behaviours
* not excessively replicate things that the Metroid series has already done
* not be excessively difficult to program

I have had one other idea - a motile plant that would occasionally lash out at small bugs. This is neat because the bugs aren't actually enemies; they'd be tiny sprites that wouldn't affect the player except in how they trigger behaviour in other creatures. But, this is also considerably more complicated behaviour than I'd normally go for, as now I need an enemy that tracks other sprites than the player.

Making the creatures be suitably alien is largely just a matter of coming up with the right model for them (I'm making 3D models for these, then rendering down to 2D to make sprites). It's going to be a lot of work, but I'm confident I can achieve results that will look satisfactory for the non-humanoid creatures at least. See the walker I mentioned earlier, for example, or this guy.

Thanks for the offer of help. I'll keep coming here when I get stuck, but it'll be a long while yet before I have anything presentable. This is very much a long-term project.

Let me rephrase what I said about AI complexity: I just don't want them to be too complicated. I'm going to have to write the AI for all of these, after all.

Herding behaviors would be a problem because the player is not going to want to be herded, so to be at all effective, the creatures would have to coordinate with each other. Squad tactics are a bit complex for what I'm going for. I've also no plans to implement status ailments, or cover. Have you played any of the 2D Metroid games? The games are very zoomed-in, and there's usually not room for more than a handful of enemies onscreen at any given time before things start feeling very cluttered. I really am going more for non-aggressive creatures here; some of them will notice and react to the player, yes, and some of those will actually attack the player, but most creatures are there to get in the way. The focus of the game really isn't on combat, outside of boss rooms.

I'm not trying to say that I don't want your ideas; I'm just trying to clarify what kinds of ideas I'm looking for. I do like the "swarm of many tiny creatures" concept - that's are one area where I should have an advantage over the actual Metroids, as I have more resources available. Nets and other "lairs" could also be interesting. And while I'm not certain how exactly I'd do a mimic without making players think that it's just a joke monster, it's an interesting idea as well.

You could look into Abe's Oddyseus for inspiration. Some enemies only attack you when they're in groups, if they're alone they back off, and only attack when cornered. Other enemies are solitaire, and will attack each other to prove their domination, which often gives you some time to escape. And others are initially sleeping, and only wake up when you move past them too loud/fast. That sort of behaviour really made each enemie feel distinct and natural to me.

I don't think using movement schemes and enemy roles similar to Metroid would put off players; as long as the game is somewhat fun and engrossing, they will think about playing, not about other games.
If the graphics and setting are good and not obviously copied, even obsessive Metroid fans (a minority of the minority) are going to think "Derakon is conforming to a great, familiar style that I like", not "Derakon is unoriginal and I should be playing Metroid instead".
The fact that Metroid uses all good enemy patterns doesn't reduce your right to use them too: you want to make an entertaining game, not to showcase fruitless novelty.