TL;DR: Great light strategy game that will be very addicting for the first few hours for most. In a nutshell, it is a turn based strategy game in which you must complete levels to unlock new and better stuff, to be able to accomplish new and harder levels! Standard procedure really.
Please note that I mainly played the PC version, and have limited experience with the mobile version (which is for the most part very similar).
Breach and Clear (B&C) is a port of what was original a mobile game (IOS, Android). It does have added content, however its origins still show through its simpicity. The graphics are decent and hold up to HD displays. but this the main improvement. It depicts multiple representations of real world Special Operations groups in a variety of environments, with the player being the commander that holds an eagle eye of the battlefield. The authenticity of much of the info in the game (such as the loading screen tips) is indeed relevant and true to modern day SOF, although the "tactics" the game pushes aren't necessarily completely accurate due to the reliance on user input of what to do.
Technical Performance: Although I am running this on "gaming" (albeit aging) hardware, it should hold up on almost any machine at a very nice framerate. There's really nothing intensive computationally in the game. Loading times between levels are minimal. The only adjustable settings in the graphics section are antialiasing (up to 8x), game resolution/full screen, and vsync.
Starting out: There are 7 factions (squads) that you can choose from to customize, each with their own unique skill boosts. There's no context on why one might be better than the others, so it's essentially just luck. There's no reason to slave over the decision, I'd recommend just picking the squad you think looks the best aesthetically. You then select from a multitude of soldier types to fill your squad. This decision matters quite a bit as each has its own special abilities that have huge value on the battlefield. As long as you pick a variety (one of each), again don't think too hard about it. Afterward, you go through a relatively short tutorial that shows off the game's mechanics and basic strategies. Very easy to pick up, unlike some strategy games that overload my brain (and processor) from the get-go.
Entertainment value: I personally wore out most of the game around 10 hours, going through every mission (7 total) and sub level (5 per mission, making 35 total playable stages without DLC) at first on normal difficulty then attempting them on insane. I've found that insane generally is actually quite doable for the most part, although on some levels (especially on the "escape plan" gamemode) they are quite impossible to perfect. There are 3 game modes: terrorist hunt (eliminate all hostiles), bomb defusal (reach and defuse one or two bombs), and escape plan (get as many squads members as possible to a position on the map). Each gamemode reuses the same missions and sub-levels, however the initial position of your soldiers varies. The reuse of the stages does get tiring eventually, but each stage provides enough enough entertaininment for a few plays. At the end of each sub level, player performance is rated on a scale of 1-4 stars, 4 being perfect or somewhat close to it. Criteria (as far as I can tell) is the time spent and how many squad members went down during the course of the sub level (this is the larger of the two criteria). Stars actually matter as they unlock the ability to purchase new guns (all accessories and gear are unlocked at default. Completion of a sub level also awards a certain amount of money, which can be spent on better equipment (guns, gear, etc).
-As a little side note, it's interesting to see B&C incorporating a lot of big name brands into the game, such as but not limited to Crye Precision, Tyr Tactical, and Surefire. Even if the company doesn't have a nod, their equipment is still featured (LBT 6094, Giessele triggers, and a LOT more). This defintely is a seldom-seen feature that adds a authenticity.
One of the flaws I see in the game is the lack of thought as far as gun and equipment upgrades. It's somewhat 2-Dimmensional, as there is often a clear "X plate carrier is better than Y plate carrier in every category". It seems almost carelessly done, as it significantly dims the strategic value of many purchases. In the end, out of the 18 long rifles featured, I purchased maybe 10 of them, skipping from the default rifle (M4 carbine) to some of the higher end guns by patience and thriftiness.
Gameplay: Quite fun, but reptitive after everything worth buying is unlocked. Each turn is worth 5 seconds, and works in a way similar to Fire Emblem. You start each sub level by picking from 1-4 entry points that your troops can breach through, and work your way to the objective. Each soldier has a movement range, effective firing range, etc depending on their stats and equipment, so each squad member has the potential to be very diffferent from the next. Sub level design is actually quite thorough, albeit somewhat linear at times. Usually, there are a few ways to approach an objective, through different paths. Object placement is realistic, and although this sometimes does not work out tactically, the developers really try their best to keep gameplay relatively balanced. Experimenting with new unlocks in different situations also adds to replayability, however in the end there's really only a couple of guns that players might choose to switch betweeen as they are superior to all others. I feel that some of the elements of the game, such as stealth, do not matter in the end. The developers seemed to have added them in as they are viable in real life, but the way the game works makes it relatively ineffective and I end up shooting my way through every mission anyway.
Plot: There is no plot to B&C, not really even a true attempt at one, however this works out for the game. There are 7 "missions" that take place in different countries/stages, each with 5 sub-levels that have short descriptors which are essentially formalities.
User Interface: The UI is especially important for strategy games as it can be confusing for newer players who have not learned what each button does. However, B&C is a relatively simple game that, once you go through the initial tutorial, you've pretty much mastered the controls. Everything is very intuitive and well organized.