Formations with an OHQ (brigades, corps, and armies) have to be discovered and researched similarly to all techs in Shadow Empire. Unfortunately, there is no in-game tech tree. This guide addresses that.

A few words in advance:
All formations in Shadow Empire use a system where you first have to discover a formation before you can research it. Which formation you discover is randomly chosen from all formations that you can discover - you have no control over this. After a formation is discovered, you can then research it. As you can't control which formation you discover, limiting the amount of possible discoveries is essential in order to quickly discover and research the formation you want. There are almost a hundred formations in the game. Just researching everything will see you take forever to get the one formation you want - be picky in which ones you research!

There are generally two types of formations: Infantry formations and tank formations.

All Infantry formations have mostly basic infantry, but can swap out some of the basic infantry for MGs, RPGs, towed artillery and light tanks. It is possible to upgrade or downgrade from any infantry formation to another, however you will have to follow the tech tree up or down.

Every basic infantry formation also has a "heavy" variant that roughly halves the amount of basic infantry and doubles the amount of specialized infantry/equipment. In addition, all infantry formations have a motorized version that includes enough trucks to move everything and a mechanized version that includes enough APCs to move everything.

For tank formations, there are four general formations: light armor, medium armor (can also use assault guns), heavy armor (can also use monitor tanks) and destroyer. You can not upgrade/downgrade from one of these formations to another (so no switching from light armor to heavy armor).

Tank subformations add infantry and various specialized infantry or equipment, as well as enough trucks or APCs to move everything.

These are all infantry heavy formations. In general, all infantry brigades have a total of 5500 soldiers. Infantry formations then swap out normal infantry for specialized infantry (machine guns and RPG) or other equipment (light tanks and artillery). Infantry formations can't include medium or heavy tanks or other vehicles like that.

You need to first discover and then research a formation before you can discover and then research the formations below that. You also have to have at least one model for each model type discovered before you can discover a formation requiring that model type.

For example, to discover Storm Infantry, you need to have at least a single light tank and an artillery model developed, as well as the Assault Infantry and Siege Infantry formations researched.

You always start with at least Light Infantry and MG Infantry researched. Higher tech starts have more formations researched.

Every basic infantry formation has five subformations: a motorized (trucks) and mechanized (APC) formation, as well as a heavy formation and its motorized and mechanized variants.

Researching a basic subformation unlocks the motorized and mechanized formation, as well as the heavy formation. Researching the heavy formation unlocks both the motorized and the mechanized heavy formation. Researching the motorized formation also unlocks the motorized heavy formation. The same goes for the mechanized formation.

Researching any of the basic tank formations unlocks the Grenadier, Assault and Infantry formations for that armor army type. These always include enough trucks to move all the additional infantry or artillery. After researching one of those tank formations, the mechanized formation (with APCs) is unlocked.

Be careful with the naming of the Heavy Armor formations - it can easily be confused with some of the Heavy Infantry formations. A Heavy Mechanized Armor Assault Brigade is something completely different than a Mechanized Heavy Assault Infantry Brigade.