Sadly, it has been over a year since the OP first started this thread, and without any real interest.
If the OP ever logs back in, I hope to see a few more details, such as (1) Which version of D&D, (2) which classes and races are open to characters, and (3) how will the actions be presented and resolved.
I have played and referee’ed play-by-post RPGs, and there are other difficulties involved.
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.