[Feature] Era Mechanism

[emzinnia]

Eras are one of the key forms of progression in Clickopolis. They get unlocked once you meet one of a possible criteria (aka defeating enough enemies, gaining enough buildings, unlocking enough technologies).

Acceptance Criteria

• Document/figure out some of the mechanics for Eras
• Uses the following eras
  • Ancient
  • Classical
  • Medieval
  • Renaissance
  • Industrial
  • Modern
  • Atomic
  • Information
  • Future
• Starts with support for Ancient era
• Decide on a mechanism for advancement into Classical era