Leveling up and unlocking new skills has been one of the cornerstone mechanics of the Zombicide Board Game franchise since season 1 modern was released.
Kill zombies, gain experience, and cross over into the next threat level- yellow, blue, red, orange, etc. A new threat level gives you new actions and skills to use, which is balanced out by spawning more zombies with each spawn card.
Some mechanic in Invader…
…but the tempo is *very* different.
It’s taken me a dozen or so plays to figure this out.
One of the rules changes/evolution in this version is the use of bots and sentry guns. They don’t count as survivors for the mission, but they can be activated and controlled- with the experience going to the controlling survivor.
They are quite powerful, very useful, and are pivotal in many missions. But passing on the experience means that controlling character levels up quite fast- pushing the threat level before the other survivors are ready to also level up.
Less skills and actions for them, while more Invaders are spawning.
There are ways, considerations, to counter this- normally XP giving items like MREs- food and rations in other games, get consumed right away. Now in Invader I find I’m holding them to boost characters as needed. Same with spreading out the experimental weapons.
Equal leveling seems to be even more important in this edition.