Echo Generation is set in the 90's - an era of televisions and landlines. The televisions in this game hold clues to a puzzle which, when solved grants additional power in battles.
Echo Generation has a bunch of creative puzzles that sometimes can span multiple areas and transcend the self-appointed quest you're currently tackling in and around Maple Town. One of these puzzles will take you all the way from your own home to the principal's house, then to the repair shop and finally to the graveyard.
The typewriter tombstone puzzle code
The tombstone in question lies on the outskirts of the graveyard and has a couple of distinct features: first of all, it's for a human and second, it glows with an orange hue. Cracking this tombstone's code will permanently make you stronger in all battles to come.
Your first clue will show up in the principal's house. This house hides many secrets but for now, we're focusing on the big tv right next to the side door. Toggle it on to reveal your first clue. The shape will be different on each playthrough. Make sure you also snag the doll from the cabinet on the left. You can give it to the strange puppet creature near Billy's Garage.
Speaking of the garage, that's the place you'll find the second clue. Go around, or fight the creatures guarding the entrance and go behind the counter. There's also a safe there: the combination is "3122" and there's a motherlode of cash inside.
Most players will miss the third clue as it shows up on the tv at your house at night, but it's possible to solve the puzzle without it. Just punch in the first two shapes and then complete the combo by selecting all available shapes - one at a time. Note that shapes in the combination can be repeated. It may you a few tries but once you get it a ghost of a writer will appear and grant you a pack of s'more bubble tea flavouring.
The tiny packet can be used to make bubble tea which you then give to the woman in Tea Tunes in exchange for some envigorating advice.