I definitely like the idea and the concept is close to part of the game I was working (cards taking up more space to represent size and scale).
I did encounter a glitch though. Since two-skull monsters take the whole field, you can't play new cards until they die. That's fine, but then when you skip the Play a Card Phase (because you can't play cards) into the Attack Phase, the Phase is still locked into Play Cards Phase (says "Play a Card" in the corner still) and won't let you click on your monster to attack with it. End Turn is your only option and it just gets attacked each turn with you unable to do anything unless you can play a card. Also, I couldn't seem to sacrifice Two-Skull Monsters backdown to One Skull so I could at least attack again. (I already know you can sacrifice a One-Skull for another One-skull to use the monster before death, because I did it.)
I imagined this works just fine as a tabletop version, albeit having to figure out the card size part. I thought about using bigger blank template cards to test it rather than smaller blank cards to fill the spaces but both would work.