From Halopedia, the Halo wiki
Supplies are the primary resources used in Halo Wars and act as the basis of the game's economy. Supplies in Halo Wars are similar to resources in the Age of Empires titles which Ensemble Studios also produced.
In order to acquire resources, supplies must be ferried via supply ships to UNSC supply pads or through the use of gravity lifts to Covenant warehouses. Additionally, supplies may have been dropped on the battlefield or left from a previous engagement.
To collect these resources, select an infantry or scout unit, and then move them to the supply crates. Supplies may also be gathered through the use of a Forerunner Supply Elevator which will help a player acquire resources at a steady rate as long as they are controlled and defended.
There are a variety of tactics for gaining supplies:
- Forerunner supply elevators have the same production rate as 3 Supply Pads or Warehouses. Controlling one thus frees up a base slot for another building.
- In every map, there are a few supply crates near the starting base (generally ~90 supplies worth). While they may not be much, they can help turn the tide in the beginning of a Standard game.
- All Rebel-held structures leave behind additional supply crates when the structure is destroyed (in the case of bases) or the rebel occupants are killed (in the case of occupied structures).
- An upgraded Supply Pad or Warehouse produces supplies twice as fast as a normal one.
- Sergeant Forge builds Heavy Supply Pads right away. While more expensive initially at 225 supplies vs. 100 for normal supply pads, their cost overall is lower, as the upgrade alone costs 225 supplies.
- An extra Covenant base, upgraded to a Citadel, can be converted entirely to resource production, with one shield generator and turrets for defense. The main base can produce any special troops for defense, if necessary.
- Covenant leader powers drain supplies quickly - make sure to back them up with significant production. Otherwise, your leader becomes much less powerful.
- Try to avoid using Covenant leader powers early in a game - their supply usage can ruin sound strategies.
Supplies in Multiplayer
Supplies may be shared with allies in a multiplayer game. Players may request supplies by pinging an ally's supply pad or warehouse by means of clicking the left analog stick. A player may send supplies to an ally by using the circle menu on their own supply pads or warehouses. Note that it costs 300 supplies to send an ally 200 supplies.
In multiplayer, due to the ability to share supplies with allies some players will focus almost entirely on building an economic advantage by building large numbers of supply pads and using them to help their allies upgrade and build units faster. Just remember to defend one's base!
While the supply counter will stop at 99,999, the player will continue to gather supplies beyond this level.