I’d suggest changing the last part to:
“ICBM rockets take some time to reach optimal ignition speed, so their strategic use is of prime importance.”
As for…
I think that can spice up the challenges a bit more. Darkness effect can also be included.
I’d say a random one for each mission, but the easy one should not get the lightning and darkness effect. As for weekly… Don’t use darkness or massive. (But it’s still an option if you want to)
As for frequency… Everyday? Although I’d suggest adding a bit of flavour text to reflect on the environment effects for that mission that’s to be expected. Here’s all the possibilities I can list:
If the challenge will have Massive + Hot:
"This will take place near the Sun of “name of star system”.
If the challenge will have Massive + Electric:
“You will be positioned at a geologically unstable area.”
Massive + Frozen:
“Be sure to winterize your windshield so it doesn’t crack under the intense cold and gravity.”
Massive + Darkness:
“Pursue the closest wormhole, where the Henpire are escaping to.”
Frozen + Electric:
“Violent Storms are rampaging in this area.”
Frozen + Darkness:
“This Frozen Wasteland is surrounded by thick clouds of dark matter.”
Electric + Darkness:
“Constant Storms have disrupted the dark matter in that area.”
Hot + Electric:
“Temperature Fluctuations and Storms are to be expected.”
Hot + Darkness:
“A Dying Star is nearby. Be sure to leave immediately after you’ve completed your mission so you won’t be caught in the blast!”
If it’s just Hot/Cold:
“Expect some extreme temperatures.”
If it’s Electric:
“High levels of Electricity surround this area.”
If it’s just Darkness:
“High amounts of dark matter have accumulated in that constellation.”
Just Massive:
“Gravitational Fluxes are present in this area.”
Try to do that if possible?