Resonance is an adventure game in a contemporary setting. It opens up with scenes of simultaneous attacks in large cities all over the world and then rewinds to 60 hours earlier to start the game. It focuses on the lives of four characters that eventually converge into a single story. Tolstoy Eddings is a mathematician at the Juno Laboratory where he works on a revolutionary theory with doctor Morales. Anna Castellanos is Morales' niece, but Eddings is unaware of that and regularly meets Anna in the metro on the way to work. The player also gets to see Anna as a little child as she is often haunted by dreams of being chased. Raymond Abbot is an investigative journalist who knows how to hack computers and uses unorthodox methods to gain information. He infiltrates the Aventine Hospital to chase a story about a mysterious mainframe. The final character is police detective Winson Bennet who is staking out a suspect with his partner. The initial reports of the attacks cause the characters to come together early in the game.
In the first chapter any of the four character's stories can be chosen to complete in any order. Later on, when they come together, their cooperation opens up new abilities to solve puzzles. The game uses classic 2D point-and-click adventure gameplay with conversations, an inventory, item combinations, environment-based puzzles and more complex problems that require subtle hints picked up elsewhere. When different characters are together the player can switch between them to use specific abilities. Bennet is for instance a lot stronger than Eddings, and Abbot is a smooth talker who knows how to fiddle with a computer. Players often have to switch between them to solve puzzles and inventory items can be passed around. The game is controlled through a single cursor that shows an icon when an item can be interacted with. Left clicking triggers an action while right clicking is used to examine. Conversations appear in text but characters are also fully voiced. Item combinations are done through a dragging technique.
Another important gameplay element is the use of short-term and long-term memory, available as two separate tabs near the top of the screen. Long-term memory includes a number of personal memories or stories of a larger scope. They can be dragged into a dialog drop box as a new topic for a conversation with any character. Short-term memories can be altered by the player. For instance, when a door is locked and another character needs to be inquired about it and there is no dialog option, the player can drag the door into a slot in the short-term memory tab. Next, when a conversation is initiated, it can be dragged into the dialog drop box to trigger a reaction. This can be done with any item or any part of the environment and is often needed to solve puzzles. Certain situations are time-based and characters can die, but when that happens the events are rewound automatically to get another chance. The game includes a number of in-game achievements.