Strategy games arguably make up the most cerebral genre in gaming. Puzzle games might test your logical and creativity skills to a degree, but nothing will make you feel more like a true tactician than when you overcome a difficult strategy game campaign. If you want to test your mettle, these are the games to play.

Not all popular strategy games are made equal. Save for a few exceptions, the most popular games are rarely the most difficult. Ready to distinguish yourself from the masses? Here are some of the toughest strategy games ever designed. Try mastering all of them.

1. Frozen Synapse

Availability: Windows, Mac, Linux, iOS [No Longer Available], Android [No longer available]

Frozen Synapse is proof that indie strategy games can be so much more than simple and generic. It's a shining example of gameplay that's easy to learn, difficult to master, yet fun no matter how skilled or unskilled you are.

In this turn-based strategy game, you control a squad of combatants in an effort to eliminate all enemy units. Sounds simple enough, right? What's great is that you can simulate the actions of your current turn, allowing you to see how it might play out. When you're satisfied, all turns are simultaneously resolved.

You'll be pleasantly surprised by the enemy's smart AI, but if that isn't enough, you can also play Frozen Synapse online against other players. If you like strategy games, Frozen Synapse is a title that you need to check out. I guarantee that you've never played a game quite like this one before.

2. Commandos 2

http://www.youtube.com/watch?v=V_d1BY53Mb8

Availability: Windows, Mac, PS2, Xbox

Commandos 2 is an older game, released way back in 2001, that hasn't aged very well but definitely belongs on any list of "hardest strategy games" as it's considered to have one of the steepest learning curves of any game of its kind.

In it, you control a squad of commandos who must rely on tactical positioning and advancement to accomplish a number of objectives. Don't confuse it for a turn-based game, because it isn't. Don't confuse it for real-time strategy, because it isn't. It falls best under the category of "real-time tactics" game, which is something of a hybrid genre.

For the best experience possible, most recommend playing the PC version as the gameplay controls aren't very intuitive in the console alternatives. If you want more like this, check out our list of the best war strategy games.

3. XCOM: Enemy Unknown

http://www.youtube.com/watch?v=JmwkNvhthZc

Availability: Windows, Mac, Linux, PS3, X360, iOS [No Longer Available], Android [No longer available]

The very first game in this series, titled UFO: Enemy Unknown, debuted way back in 1994. Since then, a number of games have been released under the X-COM franchise up until around 2001. After a long break, the franchise was revived under the XCOM franchise with XCOM: Enemy Unknown. Was the wait worth it? You bet it was.

This turn-based tactical game has the player controlling a squad of alien-fighting soldiers who must defend the Earth from an imminent invasion. You play through a series of missions which are interspersed with phases of research, development, and expansion. And to top it all off, critics consider it to be one of the most challenging tactical strategy games of this generation.

If you enjoy this game, continue the fun with the expansion pack, XCOM: Enemy Within.

4. Xenonauts

http://www.youtube.com/watch?v=iOusl2XwYmM

Availability: Windows

If you know anything about Xenonauts, you'll know that it's suspiciously similar to the aforementioned XCOM series. Well, that's because it was indeed heavily inspired by it, though that doesn't mean that Xenonauts is a sequel. The theme and gameplay are similar but it is neither a clone nor a remake.

Xenonauts gameplay is divided into two distinct components: there's a strategic element that involves real-time air combat and a tactical element that involves turn-based ground combat. On top of its XCOM influence, the game has made some playability improvements of its own, including a cover system in combat, starting combat formations, and alternative victory conditions.

5. Europa Universalis IV

Availability: Windows, Mac, Linux

The Europa Universalis series of strategy games is among the deepest and most involved in its genre with Europa Universalis IV being the most advanced yet. Like the Civilization franchise, there's a surprising amount of depth here, particularly when it comes to the sheer number of actions and options available during gameplay. Thematically, it covers a wide time period ranging from the 1400s to the 1800s.

The general flow of gameplay begins with exploration and scoping out the unknown world, which then moves onto expansion of territory, exploiting the world's resources, and finally exterminating your opponents. Europa Universalis IV is the very definition of a 4X strategy game, though this game has a lesser focus on direct combat and a greater lean towards diplomacy than most other 4X offerings.

Once you beat the original game, you can expand content through 3 expansion packs and over 10 different downloadable content packs. Or if you'd rather play against people, you can do that through the multiplayer feature.

6. Sins of a Solar Empire

http://www.youtube.com/watch?v=LSmALqe4dqk

Availability: Windows

Like the aforementioned Europa Universalis series, Sins of a Solar Empire is a real-time 4X strategy game that takes place in the future when civilization lives among the stars. Through military and diplomacy, players can conquer various star systems to advance their own empire.

One of the defining aspects of Sins of a Solar Empire is its massive scope. The 3D environment, just like true space, is an entire ocean full of celestial bodies with which you can interact. The difficulty of this game comes from the depth in all of its technology trees and game systems; there's so much to do that a single game can last over six hours.

Sins of a Solar Empire is primarily a multiplayer game. While no single player campaign exists, you can play against AI opponents in an offline mode when multiplayer is not an option.

Know of a strategy game that's even tougher than the ones listed here? Share them with us in the comments and make a case for why you think so. We'd love to hear what you think.

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