Just in case our esteemed mod-devs are short on ideas, I'll just leave these here:
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FFA Allies- FFA, but after ten minutes players are assigned an ally
- Alliances could be random, or balanced based on army value / economy
Team Chaos- Teams, but after 10 minutes 20% of each team (minimum 1 player) is changed to be a member of the other team (time and percentage are configurable)
Team Traitor- Teams, but at the start of the match 1+ player on each time gets a notfication they are the traitor
- At 10 minutes traitors get switched to the other team (configurable)
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Monster madness- Every second, commanders spawn a basic chicken next to them
- You get 1 or 2 metal and energy every time one of your chickens does damage to an enemy unit or structure
- Buttons exist to upgrade chickens HP, attack, speed, spawn rate (costs metal+energy)
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Team chicken- Each team automatically gets a chicken ally (spawns roost and has waves as normal)
- Buttons exist to upgrade chicken tech progress, wave frequency, queen stats (costs metal/energy)
- Roosts supply less resources to their team than in standard chicken mode
- Win by killing queen or other team
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Air drop- In addition to or instead of mexes, there is randomly located wrecks of increasing value that drop out of sky, and must therefore be fought over
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3-team and 4 team Zero-Wars maps- Waves targets random or alternating enemy team
- Could autogenerate depending on number of teams, similar to autogenerating FFA maps
Supply Routes-Spawn supply vehicles that need to travel to your mexes and then back to earn metal, changing raid/defence meta and just looking cool.
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https://zero-k.info/Forum/Thread/38609