It's a four-page thread I posted recently, but it does provide some valuable insight on exporting to Android (in it's present state) in Construct 2. Be aware of the "problems" it poses before you decide to go all-in on your project. -- scirra.com/forum/bottom-line-construct-2-and-the-ouya_topic62988_page1.html
"Problems" aren't the fault of Construct 2 exactly, just in the way it handles exports to mobile. You may not get 1:1 of what you're looking at while you're building the game on your PC. Me personally, I came to the conclusion that "In order to make a well-functioning .exe that doesn't piggy back any unofficial third party plug-ins that you must troubleshoot/wait for their respective development team to iron out, you're best off going for a straight PC Title using Construct Classic. Added benefit that Construct Classic is free, double bonus (for what I'm doing) is that it doesn't rely on HTML5 but rather Direct X 9."
With all that in mind, I've been playing games since 1988. I do like to help pitch ideas as well as give "historical" insight with my large (useless) knowledge of games and stuff that went into their successful and unsuccessful designs. Nothing here's a criticism of you/what you're doing, I'm just trying to help out!
Here goes.
--A Series of Characters w/ Unlockable Skins--
Something that modern "3d titles" have put into people's brains are that "skins are easier to do than all new models". This is NOT true of 2D... the way they got around this for decades (even into the "3d era") was to palette-swap the main character. Most famous example would be Scorpion/Sub-Zero/Reptile/Smoke/Noob Saibot/etc etc from the Mortal Kombat Series.
There are numerous examples of games created where ONE protagonist gains multiple abilities and simply changes color to reflect the upgrade. Consider "Mega Man", "Metroid", "Super Mario Brothers". It wasn't until much later in each series that their protagonist's actual appearance changed, but nobody questioned that "white and red" mario = Fireball, or Pink/Purple Samus was stronger than Yellow/Orange Samus. The big benefit here (for you) is that you only have to create ONE set of animation, and later if you choose, simply recolor them to reflect advancements. If you wanted to, say, include even just ONE additional "character", you are effectively doubling your work in this department and tacking on the additional time to your overall development cycle.
--Breakable Scenery Objects--
Simple stuff. Create the object (let's say it's a glass window), then set it to, upon colliding with your character, destroy and spawn multiple instances of object "shattered glass". Have THEM get destroyed by either falling off screen and choosing the "Destroy Outside Layout" behavior for each glass shard. That means once they fall off screen, they are removed from memory and life goes on.
The big question here is, "of what genre will your game be?" Obviously there are no big sheets of glass to smash through in a prehistoric/cave man title, and there may be better things than glass to use in a deep future/sci fi setting. It'll help if you decide early on what fixed perspective you will implement... Canabalt, for example, was side-scrolling but had a slight (45 degree?) angle about all of the scenery that didn't change. So did the infamous Battletoads motorbike sequence. So did Prince of Persia (the original, not the new stuff. I will rarely refer to new stuff.)
Mega Man did not. Super Mario Brothers did not... but all they were interested in was the platforms, not the objects that you collided with: There were simply blocks and blocks and blocks... If you're looking head-on with the world detail, you may not fully see the "glass plane".
That said, think on this a bit.
--Simple Equippable Item/Inventory System--
Such as? I mean, it's a non-stop running game right? Part of having items/power ups means integrating their use into your LEVEL design. Assuming that your characters will never "fall into a pit because the gap was intentionally made too wide for your standard jump" is, well, cheap. And a dealbreaker in many cases. This creates artificial difficulty, nobody enjoys that.
What makes powerups "work" in a traditional platformer like say, Super Mario World is that "Yes you can fly if you run long enough, then rock back and forward on the D-Pad to maintain/increase/decrease your height. If you fly in the RIGHT places, you can find platforms, 1UPs, or secret stage exits". Apart from something that, maybe, allows you to recover from falling or (if you're planning on this) shake off damage incurred by enemies or certain destructible objects, I find it hard to imagine how power ups would be a "help" to your game. Have a powerup that makes a character run faster, and you'll have to design -all- of your platforms to be able to "catch and release" the player with enough space to facilitate both the standard run speed and enhanced run speed. Same for gaps. By planning some of your stages to have "quick hop" segments (where timing is everything to land on little platforms", you may end up breaking those sections by turning up the speed too much.
Same with a boost for jump height. You may send players "well over" their intended platform, forcing them to fall into a gap following the landing zone.
I'm not saying there's not powerups that -will- work, it's just... "would they work for an endless running game? Or would they work for a platformer? They're two different genres for a reason."
You would have to meticulously design each level to use a powerup featured on that level in order for such a system to pay off and not become an exercise in frustration as players try to use these "boosts" only to discover "that one keeps killing me." Players would eventually take to disregarding those powerups, which means disregarding your hard work. These difficulties are compounded when you consider that you want...
--Randomly Generated Scenery/Terrain--
This goes hand-in-hand with your powerups as, well, randomly generated terrain more-or-less guarantees a standard set of powerups will be useless... or that those powerups will have to be so vanilla that "they all work for all occasions equally". Something like point multipliers, or distance ran multipliers (which for my liking doesn't sit well if distance ran is a factor in your game). Your scenery generator will most likely end up focused on creating seamless levels, and not "levels that encourage powerup usage, and KNOW what powerups the player has when taking tilesets into consideration".
Random is good, it adds a challenge for sure. Nothing wrong with memorization/rhythm, but if random's what you want then be prepared to put in the extra effort to strike a balance between "ever changing" and "meaningful."
--Thoughts That may Help--
Okay, so maybe I -will- mention a modern title. Have you tried the endless running game "Pitfall", based on the Atari 2600 David Crane classic of the same name? The game is an endless runner that shifts between a "behind Harry" view and a "side scrolling" view. Your standard list of commands are to swipe UP to jump, swipe DOWN to duck/slide, and tap the screen to crack your whip (for fending off enemies on the track). When you're in the "behind Harry" view, the same as above, only now you can tilt your device left and right to shift Harry left and right along the track as he runs forward (away from camera).
Of all the endless runners I've played, "Pitfall" is my favorite. By a large margin. Not just because of the art style, but because of how damn varied the gameplay is. As you make your progress, you are constantly coming across new forms of obstacles... bridges with sections missing, hopping on the back of a motorcycle (You can baseball slide with the bike but not jump... hit ramps instead), jumping into a minecart inside a volcano with lava far beneath you (here again you only really have to duck to avoid most obstacles), hopping on top of a bull that smashes through enemies/objects and basically "auto-runs" the level for you for 200 feet or so.
Maybe "Powerups" aren't the way to go. Maybe vehicles? Animal companions? Robots? Spy Gadgets? This would kind of provide the "Feel" of different characters/skins but saves you the effort of providing a full sheet of separate animations by simply keeping each player add-on/companion set to a specific task. A jetpack, for example, could fly you ahead with no effort a set distance. All enemies/hazardous objects can be avoided through normal means (ducking, jumping) but perhaps can be blasted away with a weapon not included with your default character? But even then, for what exactly? Is there going to be a points/rewards system? Extra lives, or what have you? Maybe including the means to DESTROY an object gives you points where avoiding them gives you nothing. That's incentive right there for a player to not only locate the weapon, but learn how to use them.
I'd be happy to bounce the ball back and forward with ya, feller... I can get more specific with more specifics.