Probably my initial favourite of the 3 Osprey books to land on my doorstep lately, Zona Alfa is a a pretty straightforward game for playing 28mm S.T.A.L.K.E.R and Metro 2033 skirmishes - you know, post-apoc Russia in "The Zone" - home to mutants and radioactive artifacts.
It's a typical 64-page Osprey Blue Book - softcover, with bits of Osprey art and photos of minis. It was quite dense with a high text:image ratio. It had a good table of contents and I found it easy enough to use and navigate. 3.6 roetengen - not great, not terrible.
It plays on a 4x4 table, using 4-12 minis from any company. The rules are cheap and it uses d6 and 4+ d10 dice. It's pretty cheap. You'll need 4 types of tokens for status markers. A fair bit of terrain would be good, but you could use most WW2-modern or ruined buildings. The rules are pretty consistent, simple and logical. Models have 4 stats - Move, Combat (a mix of shooting/melee skill), Armour and Will. A good mix. The core rules are 24 page long and there's only a dozen special rules. These rules are cheap and very accessible.
Initiative & Activation
It's alternate activation, with no rules for mitigating bigger forces (i.e. the more numerous side tends to get a tactical advantage with unopposed moves). It revives the old (early 2000s?) "action point" system; basically rookies get 1 action (move or shoot); a regular 2 and a veteran 3. Basically, better troops can do more stuff, and start with more skills.
Once activated, soldiers can choose to shoot, move, aim, climb, reload, remove pins, etc as an "action" or reserve an action for later (aka overwatch) at the cost of two actions. Some complex skills like defusing bombs require a "Will Check." This is all logical and solid without being amazing.
Models get a 360 FOV (I prefer 180 as it adds more choices at the no real extra complexity). Obstructions, soft and hard cover add modifiers to firing and even Will. Troops move individually except pack of rats, etc which have a 1" coherency. There are climbing and jumping rules. Again, very simple.
You roll a d10, and score equal or less that the (modified) Combat stat. Rolling low is a little odd, but I can't complain as I've just been using it for my own homebrew rules.
Any hits can be "saved" by the defender rolling equal or under their Armour (minus any weapon bonuses).
Melee is simultaneous - a defender gets a free "fight back" - which means both models can take each other out at the same time - which I'm not a huge fan of. Attackers (active player) can use their hits to cancel defender hits which should favour the attacker.
Rolling low is a bit unusual, but rest is simple & consistent - but not a huge fan of the melee rules.
There are successful damaging hits, and those deflected by an armour save. A successful hit wounds which knocks out/removes most non-hero models (mitigated by medikits). A deflected hit causes a Will Check - failing this roll collects a pinned token. A hero with a wound halves their speed and combat stats. Pinned models cannot do anything except defend themselves and remove pinned tokens by using actions in their turn. This is again, simple and straightforward.
Gear, Skills, Squad Creation (Necromunda-esque stuff)
There is a decent, logical range of armour and weapons from teeth, claws and machetes to assault rifles, flamers and HMGs and grenades. There are 8 weapon special rules but they are logical - like "Reload" - the weapon (say a RPG) must reload after each shot.
Troops choose from a restrained 11 special skills and can choose from 15 pieces of equipment like binos, gas marks, anomaly detectors etc.
Crews are bought/balanced based on total actions (i.e. a squad of 4 rookies would be worth 4, while 4 veterans would be worth 12). You can also "trade" an action and raise a single stat of a model by 1. I.e. instead of paying 3 for a 3-action veteran, you could pay 3 for a 2-action regular with a +1 combat stat.
Factions include traders, scientists, military, independents, cultists and bandits which come with their own squad pros and cons. They can be allied, neutral or enemies to other factions.
Crews collect "advances" (like XP) and can improve stats, equipment and skills; which can also be purchased with cash. Wounded/downded models can collect injury effects. You can buy new gear and weapons for cash and hire new recruits. It's a typical Necromunda/Mordhiem system, but on the light side.
The missions themselves have "threat levels" based on how far you go into the Zone. "Hot Spots" are marked places on the table that can contain loot or threats - more dangerous missions have more hot spots with more risk vs reward dilemmas. Hot Spots can be triggered by base contact or a "bolt toss" (a tribute to STALKER) and spawn random hostile mobs which must be eliminated before the area can be searched for salvage. Sometimes a hot spot can trigger a dangerous but valuable anomaly. This must be cautiously searched using a Will Check (and a detector) to collect rare artifacts - or suffer dangerous effects.
The missions themselves are more suggestions - Zona Alfa is designed to be played with mates, creating your own stories and missions, rather than competitively. There's a mere three fully fleshed out mission examples. The hot spots and Zone threats are cool and give a STALKER vibe, but there's nowhere near enough "proper" missions.
TL:DR Recommend? Yes
There's nothing new or exciting but it does what it says on the tin - deliver a simple, unobtrusive set of rules that don't interfere with playing a game. Its consistent mechanics and sensible amount of special rules means it is an easy game to teach to newcomers or as a club game. It has a reasonable campaign system and interesting "Zone" mechanics, but lack of proper missions are a drawback. It's not an exhaustive, complex ruleset, and is clearly aimed at narrative, not competitive play. If you want to get minis on the table, and game a campaign in the "Zone" - then I can strongly recommend Zona Alfa.