It's also important to upgrade your cards. As you play you'll sometimes earn fuel as quest rewards. You can use fuel to upgrade both soldier and action cards to make your soldiers stronger and your action cards more potent. You also have the option to buy fuel for real money, but I found it was pretty easy to earn it just by playing.
Freemium concerns and other issues
In the beginning, you start with 140 energy, and each mission you play uses up 20 energy. So by that math you'll get to play seven missions before you have to stop or buy more energy for real money. But each time you level up as a player, the game refills your energy to full, so you won't even hit your limit for quite awhile.
My concern is about later in the game, when it takes longer to level your character and the energy refills are few and far in between. At this stage of the game, I imagine the energy limits will get frustrating unless you're okay with waiting it out. For the most part, the freemium model will not be in your way, but be aware that later it will become a problem.
The other issue I had with this game is that it's almost impossible to read the text on cards on the smaller iPhone screen. A recent bug update says they should be more readable, but I didn't see much of a difference. On the iPad, it's no problem at all, but it's worth mentioning if all you have is an iPhone or iPod Touch.
The Collectables is an excellent action-based strategy game with amazing looking graphics, a fun action movie storyline, and tight gameplay. The touch controls let you control your soldiers individually or as a group, making strategic maneuvers possible and immensely satisfying to pull off.
Though it's playable on the iPhone, the small screen size makes it a bit crowded, and you're going to have trouble reading some of the smaller text until the developers provide a fix. On the iPad, it's excellent.
Late in the game, once you've invested a lot of time, I think energy will start to become an issue. The only way around it is to spend real money, or wait until your energy builds back up. Still, as long as you have a little patience, The Collectables is an outstanding game, and it's perfect for anyone who wants a balanced mix of action and strategy.