Nice
This is a very nice remake of Minecraft in 2D, except that there's already one similar to this called "Terraria". However, since that's not based upon Minecraft, I'll not push this further; I'll focus on this flash.
The graphics: They're not half bad, and it's good in my opinion; however the character's design could be improved on, but apart from that, it's not that bad, it's acceptable.
The music/sound: There was no music, alas, and the sound effects were mediocre, but I can understand since it gives me the space to play other music while I'm playing this game.
The gameplay: It's similar to Terraria's, and that's nice, but there's a problem that may or may not be huge: the game lags like hell. I guess this could be due to all the thousands of collisions being detected throughout the game, but it simply lags on my 2GHz computer. And that can't be good.
But it's good for an attempt in flash, I'll give you that. I like the save and load feature; it can very much be a "poor man's minecraft" -- and this is not an insult -- I've favorited this so that I can play it when I'm bored, but please, please try to fix the lag. It brings the overall points I'd give for this game down, and I can just bet the other reviewers whining about it when they play it, since I can't see the reviews when this is under judgement.
~~ Summary ~~
~~ Good points ~~
1) Managed to pull off the 2D version in flash
2) Okay sound effects
3) Save/load feature
4) Okay graphics
~~ Bad points ~~
1) Lags, lags a lot
2) No music