Gaiaterra: Elysea's Conflict/Tier system

In The Warzone, advance infantry, vehicles, upgrades, and so on are locked behind a tier system, requiring the commander to invest resources to unlock their stronger armaments, though how is different per factions. Every faction has only 4 tiers and 3 tech levels. Each faction's headquarters initially set their alert status to Tier 0.

Tier 0
The first tier, usually known as Tier 0 and sometimes known as "Basic", consists of the basic units that can be constructed from production structures without the need of any other structures.

Some examples of these units are initial infantry (reconnaissance, basic, support and anti-armor), basic vehicles (reconnaissance, anti-infantry, armored car, anti-armor, infantry transport, anti-air, IFVs, light tanks and possibly MBTs), basic aircraft (light and transport VTOL craft/helicopters/rotorcraft, and standard multirole fighters), and basic vessels (patrol boats, frigates, destroyers, mini-subs and corvettes).

Tier 1
The second tier, usually known as Tier 1 or the first alert status level and sometimes known as "Standard", is started by the following list below. This tier grants access to advance infantry squads, vehicles, mainly tanks, and aircraft as well as sub faction-exclusive units.

Tier 2
The third tier, usually known as Tier 2 or the second alert status level and sometimes known as "Intermediate", is unlocked by primarily economical buildings. This tier unlocks heavier vehicles, mid-level aircraft, specialized infantry, sub-faction's hero units, and secondary economy structures, as well as the next tier of structures.

Tier 3
The fourth tier, usually known as Tier 3 or the third alert status level and sometimes known as "Advanced", is unlocked by Tier 2 tech building. This tier consists of heavy/advanced artillery, heavy/advanced anti-air, heavy units meant to break any stalemates, superweapons, all other locked units, and most of all the sub-faction's Epic.