Steam Ages is the 15th world in Plants vs. Zombies 2. The main gimmick of this world are sewers which come in two types. Steam sewers will first appear on the lawn with a cover, but after some time, a massive amount of toxic steam will blow and blast the cover. It will stay on the lawn till the end, making your plants in a 3x3 area around it take damage continuously. Lotus Root can be planted adjacent to a steam sewer in order to absorb the its toxic steam, however the steam sewer will blow toxic steam again after some short time, and this can be delayed for several more seconds by blocking the steam sewer with a Flat-shroom whilst synergized with an adjacent Lotus Root. Transportation sewers, on the other hand, can transport zombies similarly to tunnels, but the process of the trasnportation can be slower and are also able to transport zombies to different lanes. Flat-shroom can be planted on transportation sewers in order delay the transportation of zombies even further. The world seems to take place during the Industrial Revolution towards the end of the 18th century in Great Britain, where the use of steam and fossil fuels to power machines skyrockets, air quality plummets, and a hole in the ozone layer is created. Factories around the city repair and assemble machines, trains, and generators. It may also possibly take place near World War I where weapons seem to be more advanced due to the evolution of engineering. Like Lost City, it may have taken place during the Victorian Era due to the latter's setting (e.g. the Tower Bridge crossing the River Thames in the lawn's background) and both worlds containing British-looking zombies. It likely takes place between 1894 (the year the Tower Bridge finished construction) and 1901 (The end of the Victorian Era), although Lost City likely takes place after this world due to the invention of planes and airships.
The Plants that you can obtained in this world (My Take): Flat-shroom: Day 1 Fanilla: Day 4 Lotus Root: Day 11 Maypop Mechanic: Day 18 Icy Currant: Day 22 Convallaria Pharmacist: Day 25 Mulberry Blaster: 29 Gold Bloom: 40 Seed Packets Electrici-tea: 20 Seed Packets Olive Pit: 20 Seed Packets Electric Peashooter: 40 Packets