My son has been addicted to Minecraft for some time, and I have played with him once in a while. Once I got my head around how unrealistic some of the parts were, it is a pretty fun game.
The parts that I thought were most unrealistic (and yet, necessary for the game to exist), were the carrying physics of the character. Steve is the main character, and is representative of a normal person. Steve is roughly 2 game blocks high, and each game block represents one cubic metre, giving Steve a height of ~6 feet. Steve has 27 inventory slots, and 9 active slots, giving him a total of 36 ‘carrying’ slots, in addition to 4 places where he can fit armor (head, chest, legs, boots). Some material is stackable, up to 64 specific items in a single slot. The most glaring examples of this are cobblestone – where you can hold 64 1-cubic metre blocks in a single inventory slot.
Let’s assume that cobblestone is roughly the same density as granite. According to Wikipedia, the density of granite is about 2.7g/cm^3. Thus a 1 cubic metre block of cobblestone would weigh approximately 2700kg, or 5952.5 pounds.
If we extrapolate this out, and say that Stevie can hold 36 slots of 64 blocks each, that would work out to a total of 2304 blocks, each weighing 2700kg, for a total of 6,220,800 kilograms, or around 6000 tons.
An average person can carry roughly 1/3 of their body weight before becoming overburdened. Even if we assume that Steve weighs a hefty and muscular 200 pounds (90kg), he’s carrying too much. Alternately, if we assume that he’s not (which is logical, since he can carry all that and still run at full speed), we would have to assume that Steve weighs somewhere around 18662400kg. If that were the case, with each step he would compress the ground below him and sink down to bedrock, assuming comparable weights and densities to earth.
Regardless, he must work out.