I love Adventure Time. I love collectible card games. An Adventure Time collectible card game should therefore be the perfect thing, but then my least favorite mobile gaming mechanic rears its ugly head.

Based on the episode of Adventure Time in which Finn and Jake play a once fictional game called Card Wars, this digital version is part of a two-pronged assault, alongside Cryptozoic's physical card game, which should be in stores now-ish.

The gameplay is quite simple for a collectible card game. Both players lay down four lands, which form four corridors on the game board. They place creatures on the four spots, which battle against their opponent's creatures in the same row. If there is no opposing creature, damage from attacks goes directly to player. The goal is to deplete your opponent's health completely, after which you are declared the Cool Guy.

One Dumb Feature Kept Me From Loving Adventure Time Card Wars

Think of the digital version of the game as practice for the real thing. There is no multiplayer, just a procession of progressively more difficult opponents. Cards can be earned in battle, crafted in the game's card forge, or unlocked via special chests which require gems to unlock.

I've no problem with reasonable in-app purchases, and while Adventure Time - Card Wars' are on the pricey side — one gem costs a dollar — I've been playing for hours without purchasing a single thing, and having a fine time doing so.

What I cannot stand is this:

One Dumb Feature Kept Me From Loving Adventure Time Card Wars

See what the fish is pointing to? That is an energy meter, the most despicable method for arbitrarily restricting gameplay ever devised. Once you run out of energy, you cannot play the game until your energy has refilled. That means either waiting, or spending a gem — a $.99 gem — to refill your energy.

It's a common mechanic in free-to-play mobile games, yes. Thing is, this is not a free-to-play game. It will cost $3.99 when it's available on the U.S. app store. Who wants to pay $3.99 for a game and then be told they can't play it? Even if the time between energy points is less than a half hour, that's still time players have to wait to play a game they've paid for.

That's not mathematical at all. In fact, it's pretty much unacceptable.

It's a pity. As you can see in the video at the top of the article, I'm having a great time playing. It's got voice clips from the cartoon's characters, plenty of cards to collect, and a card battling system that's incredibly easy to pick up and play.

Thanks to that energy meter, Adventure Time - Card Wars is also pretty easy to put back down again.

Adventure Time - Card Wars!

Genre: Single-Player Card Battler

Developer: Kung Fu Factory

Platform: iOS

Price: $3.99