Really fun concept! I love the idea of presenting the player a problem that they actually have to solve with critical thinking! I think the aesthetic is really cool too! One thing you guys could consider is, in terms of plants types and biodiversity, try to pick a country/ place irl (or multiple) that you're basing your setting off of (even if the country itself has many different city environments) and try to see what would be considered an "invasive species" in those areas/ environment types. Could give an extra challenge to player!