You can't is the simple answer. They are immortal. So what do you do?
Make them mortal. Then it is about as simple as it gets.
This is the question a murderer of the gods proposed before he went around killing them. And that is the bases of this RP.
The setting is modern day. And while no the gods of Olympus do not have Temples or worshipers anymore, they are still in full swing. They go under hundreds of names each but for simplicity's sake we will strictly use the Greek names and keep it at that. Their powers are the ability to change and manipulate all matter at will. With paticular success in their specific area's of expertease. So while Poisiden can summon thunderbolts, compared to Zeus's they might as well be sparklers, and vice-versa.
Most gods live amoung humans, going about their business, making sure everything is in order and keeping the uiverse moving. After a few thousands years though most have figured out a way to allow things to run cleanly by themselves, and while yes a few nature goddess are pissed with where the world is heading, they just can't wait to let a few natural disater's build up and show them damn humans what real power is about. All in good time though.
The RP would start with Zeus calling the family to his home for an annual party. A time for everyone to get together, get drunk and hash out old fueds. You have a basic knowledge of Greek mythology (all that is required) and you'll know their are plenty to chose from.
But while the murder of gods is serious subject, I think we can fit in some tongue in cheek and as well.
Either way I have thousands of idea's and if you are interested let me know because I could go on forever like this and you just not care lol
Get in touch through PM if want to try.
Open to as group RP as well.