Research/tech trees
A branching structure of technologies unlocked over time by spending research output, each opening units, buildings, abilities, or bonuses. The tech tree is a strategy game's macro-decision spine: what you research declares your plan, and asymmetric tech choices are what differentiate empires that started identical. Designers use tech trees to pace complexity (systems come online gradually instead of overwhelming at the start), to structure eras and power curves, and to encode strategic identity (rush military tech versus grow the economy). Key decisions: tree breadth versus depth (wide trees offer strategic identity; deep linear trunks offer mostly pacing), prerequisites and mutually exclusive branches that force commitment, research speed as an economy of its own (making science a resource to fight over), and era gating. A famous refinement: Civilization VI's eureka boosts tie research speed to in-game actions, making the tree reactive to play rather than a background timer. Pitfall: a dominant path that turns the tree into a script.
- Dev effort: Medium
- Timing: Real-time or turn-based
- Common in: strategy, 4x
Seen in
- Civilization VI
- XCOM 2
- Sid Meier's Alpha Centauri