I'm just going to go through the main points you mentioned regarding this alternate reality and how I interpret the effects on Modern Warfare. I will include a lot of assumptions to hopefully assist in the development of your new world.
At the end i'll also include other items you can add.
Sewerways and pipes have become an effective mode of transport, frequently used instead of cars.
Having a new mode of transportation changes the way armies will approach the battlegrounds.
I assume the following:
- They take a long time to set-up
- They allow for rapid speed transit between locations when completed
- They are common and plentiful around the world
If you can easily transport between locations once they have been conquered, then gaining land and securing it would become a priority for the stronger army. If you can easily move nearly your entire army anywhere within your borders, distance is no longer an issue so much as army size.
High jumping skills are inherited by everyone, and landing on someone's head after jumping so high is liable to kill them.
I don't see the jumping ability to be much of a factor. The main benefit to this is the ability to squish enemies. But if technology and such exist the way they do now (but with alternate graphics), then jumping high without having the ability to redirect mid-air just leaves you as a floating target for guns. Now then, if I make the following two assumptions, I can see some significant change.
- While jumping, you can wear some decent armor without being hindered.
- There will be rapid development of technology to augment the jumping capabilities
Assuming you can be shielded and that you can redirect yourself in mid-air, this jumping ability gives every person the abilities of a low-flying drone. I can see this is creating a kind of armored infantry, but even so I don't see this aspect changing warfare significantly.
Fly Agaric mushrooms have mutated, and now give people temporary giganticism, making them almost double in size.
So this is a complete change of physical attributes. I assume the following:
- You retain normal control of yourself while under the effects
- The growth takes a toll on your body afterwards by consuming a large amount of energy.
- Any injuries sustained while large will be to-scale after the effects wear off. However, any debris like shrapnel and bullets remain the same size, which can cause additional damage.
- Times 2 in size means times 2 in each direction (much like in the mario games) for a total of 8 times body volume and mass.
- Since a human body isn't meant to sustain a body with eight times the mass, these mushrooms must also provide a significant source of energy and sustenance
With those in mind, I would think these mushrooms would work significantly well with armor to ensure that all damage is purely physical. Depending on how long the enhancements last, it could very easily become a huge resource in wars. This connects with the first point, where size of the army becomes the most important. If this can act as a temporary manpower boost at any given time, it's war-time value should sky rocket.
As a side note, it could likely have medical properties as well considering the sustenance it has to provide. Eat one and do nothing until it wears off and you should have full energy!
Some flowers are able to burst into flame, which can then be thrown.
Considering that weaponry from our current world should still exist, these flowers probably aren't that important. I would think they could help for flares or other items but it's going to be purely utility.
As fi12 mentioned, the ability to jump high and change the angle of attack easily means limiting yourself to the ground makes you an easy target. Warfare will likely be more air-based.
I enjoy the idea of having Bullet Bill's for weapons that can target lock. The idea of Lakitu cloud as well (the thing fi12 couldn't name) is also promising. It can be made so that, like in mario, it only has a short lifespan once activated.
I also see a lot of opportunity for using the other power-ups. The Star can become a drug that dulls all senses of pain for an extended time. While not invincible, the user can take a lot of hits before having to retreat. The super leaf for flying could be like a personal flight suit. While actual flight may not be reasonable, being able to jump high means you can use gravity and air resistance to easily.
Besides those, it would be interesting to see how you include Toad's and Yoshi's into the mix. Toad can easily be seen as the loyal but 2nd rate citizen and Yoshi's could be used to link the mario culture to nature (since they already use flowers anyway for resource).
Hope your project goes well!