Minion Masters is hybrid real-time strategy and collectable card game available on Steam. Players build decks of 10 cards from their collection, and then battle each other in either 1v1 or 2v2 matches. Mana is passively gained once per second and you can play cards as soon as you have enough mana available--there are no turns. In addition to your deck, you also can select one of eight Masters, each of whom has their own set of abilities.
The battlefield is divided into an upper and lower half with bridges connecting opposing players' sides. Controlling the bridges grants your master XP which unlocks further abilities as the game progresses. When playing a card, you can place it anywhere on your half of the battlefield. The AI of your minions is 'stupid' but in a consistent, predictable way--they will always pick the nearest valid target and attack it until it's dead. Combined with placement, this leads fairly organically to some interesting strategies: placing a unit with high health in front of your ranged units will protect them from being targeted while putting minions on the opposite side of the battlefield from your opponent allows you to flank and force them to defend.
At the moment there is a catalog of 95 cards which feels a tad anemic, especially when you consider that many of the cards spawn the same minions, just in increased numbers. For example, four cards spawn crossbowmen, four spawn dragon whelps, and four spawn warriors. Because the units have to have a 3D model in addition to card art, I suppose this makes sense. But in many ways, your options are quite limited. Maybe I'm spoiled--I grew up playing Magic: The Gathering which is produced by an industry juggernaut and produces 300+ new cards per year.
If you think I'm being too nitpicky, it's worth mentioning that the game is early access. Which sometimes means 'Bear with us, we're working on it' and other times means 'We're half-assing this, give us money for an inferior product. Caveat emptor motherfuckers.' And though I haven't played for long, I feel like the game is more an instance of the latter. Their business model has the sleazy feeling of a cash grab. While I got my copy for free during a promotion, the basic sticker price is $5. And on top of that, the game is riddled with microtransactions and a 'premium version' for $20 which promises to alleviate the grind required to gain new cards. That's tolerable in a freemium game but frustrating in one that charges you at the door.
It's fun enough and certainly worth the low, low price of free that I got it for, but in my opinion it's not worth $5, let alone the $20 for the premium edition. The RTS gimmick is interesting and creative but I found it wears thin after a while. Granted, I'm a poor 20-something and have never been the greatest fan of RTS games, so what I consider good value may be different from yours. But personally, I wouldn't reccomend it even to the most hardcore of CCG players. For a superior (and free) card game, I'd suggest Star Crusade.
EDIT: On further investigation, the gameplay is basically a copy of Clash Royale (which I haven't played). In addition, it re-uses almost all the assets from previous games by the same developer. Seems like a naked attempt to ride on the coattails of a popular game by churning out the cheapest possible imitation. Glad I didn't pay for this.