In addition to contests, codeforces should make puzzle hunts with teams of like 3/4 people. They could release the hunt at a certain time, and teams proceed through it like a contest. After a week or so, the hunt could close and it could be rated like a contest (but in a different rating called puzzle hunt rating maybe). Those who solve the meta-puzzle at the end could get a boost or something.
For the easter egg hunt, codeforces could hide phrases or long numbers somewhere like secretly edit the first blog post with it or something or put it in a link.
Do they have to solve the problems in order?
I don't know, that's up to Codeforces (if they even do this). Also these are more "puzzles" than "problems". A normal puzzle hunt starts with 3 unlocked puzzles and has ~12 puzzles total. Every puzzle you solve, you unlock two more. So you can solve them in whatever order given this.
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