Thanks to everyone for playing and leaving a comment, I'll make sure to try, rate and give feedback to your games as well :)!
@Larzan Thanks :)! In fact, I did develop a game with similar mechanics to Flappy Bird before, I ended up calling it Tappy Colour, hope you'll check it out :)!
Android: https://play.google.com/store/apps/details?id=maike.me.tappycolour
iOS: https://itunes.apple.com/us/app/tappy-colour/id892184447
@Jesper Oskarsson I also realized pretty much everyone, including myself, would just lean up against the walls whenever possible, which is why enemies spawn at each side on every third wave :p
As for the size of the enemies, it was a tricky choice, for the sake of gameplay I choose to keep them small so that it would be possible to spawn two next to each other and still have enough room to get past them (and I'd rather have portrait orientation rather than landscape for the sake of making it fast paced), but if you use an Android device with really high resolution (e.g. Nexus 10) then you'll get a crystal clear view of them :)!
@monsterkillu I spent the first day developing an entirely different game (I hope I'll have enough free-time to release it on Sunday), which I later abandoned because it didn't fit the 'Connected Worlds' theme at all. This ended up costing me quite a lot of time, although I'm not sure if I would have added anything else in terms of gameplay. I considered adding ability to choose player icon, power-ups (e.g. fire projectile & slow-motion) but in the end I decided to spend almost all my time making sure that performance was great, there were no bugs (at least I think I got rid of them) and that you would never encounter a situation where it would be impossible to get past the enemies. In other words, I'd rather have my game feel complete instead of having tons of unfinished features/bugs. E.g. I think the player sliding out of screen when the game is over and sliding back in when a new game can begin gives the game the kind of feel that it's a finished product.