Many people seem to think that when they spot a clone of their favorite game, they either do two things: ignore it or bash it. Usually it's bashing, but is it reallynecessary? If the game's creator really is out to clone their game, then let them be. At the end of the day, "Minecraft is Minecraft and their game and is their game" rightfully said by Facepunch user layla. And not to poke Minecraft, but Minecraft is heavily based off Infiniminer.
Here are someloosely-based games based off Minecraft. I say this because all of these games appeared after Minecraft gained success.
Manic Digger. I don't know why but it looks exactly like Minecraft. I mean, it works and functions every way Minecraft does, and it used to support Minecraft's network protocol. But now, it's just Manic Digger.
Here's a good one. Cubelands.com (domain registered on 6/26/2010). The thing I like about this are the achievements. The graphics look more vivid in this one. The picture above looks a bit touched up.
http://www.allegro.cc/forums/thread/603352 - deceptro from allegro.cc is creating the game calling it "minecraft clone".
http://www.wiremod.com/forum/off-topic/21819-minecraft-clone-improved-graphics-gui.html - Matte from wiremod.com is creating another Minecraft clone.
And the end of the day, it's what people want to play. People create their own games. The reason most people call these games clones is because they popped up after Minecraft and now they're doing the same thing over. Then again, it's basically a game where you place blocks upon blocks. In the slighest terms, that really isn't original to begin with (hence Infiniminer). But you really have to think about this, actually. Games like Halo and Call of Duty have been at war since the dawn of crack over fighting for that Top Shooting game spot in any awards show. Competition is natural and we should have all anticipated this.
I have re-edited this article to provide anunbiasedoverview of these "so-called" Minecraft clones. No hard feelings, kay?