Let’s keep things simple two rules.
- No giving sentience, This is a no brainer issue.
- Let’s keep it to beings under the Animilia kingdom. “mutated virus/bacteria” is a common trope.
To start:
Let’s modify ants to have lungs.
Most insects are constrained by the amount of oxygen they can acquire through their exoskeleton.
Imagine how big they can get if they didn’t have that constraint?
Some common form of bacteria modified to break down plastics rapidly the way they do organic matter. Youd see buildings falling apart, packaging need to be redesigned for everything, electronics rotting, etc.
bacteria aren’t under the animalia kingdom.