Very light spoilers ahead!
1. Keep an eye out for minigame tapes in terminals around the Commonwealth. You can eject the holotape and play a Galaga- or Donkey Kong–type game on the go with your Pip-Boy.
2. It's possible to visit the iconic bar from Cheers while in Boston, and it even has the corpse of a mailman sitting at the counter!
3. In case you didn't notice, you not-so-subtly find your K-9 companion, Dogmeat, at ~Red Rocket~ Truck Stop.
4. If you stare at the Pip-Boy for too long, your character will smack it a few times to make sure it works or put his arm down from being tired.
5. If someone throws a grenade at you, you can slow down time with V.A.T.S. and shoot it so it explodes safely above your head. You can also shoot grenades that you have just thrown as well for a quick explosion.
6. In workbench mode, you can scrap entire collapsed houses or cars for wood and steel.
7. Some of the most memorable quests in the game you'll encounter by starting conversations with random characters — one of our personal favorites begins by talking to Kent, who can be found in the Memory Den in Goodneighbor.
8. There's something very cool hiding in Boston Commons, so don't rush past into the station! Take a walk around the park (and make sure you have a few Stimpacks and grenades handy).
9. If you listen to the television at the start of the game, you'll learn that in Fallout 4's timeline of America, the Boston Red Sox never won the World Series in 2004.
10. Codsworth can filter drinkable water and will occasionally give you purified water if you talk to him.
11. At a craft bench, you can highlight missing parts, and when you find an object in the field containing these components, it'll be highlighted with a magnifying glass. You'll start realizing phones and typewriters are far more useful than you thought.
12. Every companion has a special skill, and it's not always super obvious — they can pick locks, hack terminals, and even heal you!
13. Your companions can wear Power Armor. It looks pretty hilarious, but they also don't use fusion cores, so load 'em up.
14. Right outside of Concord, you can take a detour to visit Walden Pond, historic home of poet and philosopher Henry David Thoreau. His "cabin" still stands by the water's edge, and you can even listen to a delightful audio tour.
15. Not every historical site is labeled. Ben Franklin's grave site is on the Freedom Trail, but you wouldn't know unless you walk up and read the name on the grave.
16. If you're wearing Power Armor, you can't swim. Instead, you'll sink like a rock and have to walk across the bottom like a total badass.
17. Codsworth has been programmed to say 924 names, so if you give your character any of these names, you can expect to hear it in a robotic British accent. There are also a few Easter egg names, like Furiosa, Fuckface, Katniss, and Mulder.
18. Ghouls' arms can be shot, cut, and punched off in battle. This will slow them down, but it won't stop them completely.
19. You can find Grognak the Barbarian and Silver Shroud costumes and weapons at Hubris Comics near Park Street Station.
20. You can't die from falling when wearing Power Armor, so you can literally jump off airships and still live. You might, however, damage your armor.
21. If you take Codsworth back to your spouse's cryopod, he'll have an emotional moment where he expresses his condolences to you.
22. You can disarm mines as you pass over them, and then pick them up and add them to your inventory.
23. If you encourage the Diamond City robot, Miss Edna, to believe in love, she and Mr. Zwicky, who is human, will get married next time you come to town.
24. If you hit X (on Xbox) when the loading screen is up, whatever's being displayed will turn bright green.
25. If you activate the "Mysterious Stranger" perk and Nick Valentine is your companion, Nick will become very excited when the Stranger appears and say he's been after him for years.
26. If you're vibing on Preston's sweet trenchcoat and hat, you can actually add and take away a companion's clothing in the trade screen. We recommend putting goggles on Dogmeat!
27. The comic books you collect give you passive perks, and you can actually build a book rack and display them in your house.
28. You have the option to un-equip your helmet in Power Armor, just in case you want to see your character's face in dialogue or otherwise.
29. Finally, your old friend the Vault-Tec rep did actually survive the apocalypse. You can find him at the Hotel Rexford in Goodneighbor, lonely and worse for wear.