TotEM Circle is a hybrid map: part theatre of the mind, part gridded battlemap – using the TotEM cards to represent key locations or things within the immediate scene.
Some roleplaying games (like the Year Zero engine) use conceptual ranges instead of exacting feet or metres, these are usually: close, short, medium and long. What's great about them is that they can flex to better suit the scene. What is short when in a Spelljammer ship chase may not be what is short in a tavern brawl. If the entire party is shrunk down to mouse size, long range may be across the kitchen. So that's what the circle represents; zones of ranges from the centre of the action. There is a space where you can write range bands down (if required), especially useful if there are ranged actors in the scene.
The centre is where the action is. It is where everyone is rushing to engage, or its the closest two opposing sides can be in a chase. Each zone from the centre takes you one range step away from the action. Although actors with ranged weapons will usually have some ability to see and fire into nearby zones. Someone throwing a dagger may only be able to throw either in the same zone, or perhaps an adjacent zone; while someone with a longbow (or sniper rifle) may be able to fire 3 or more zones away. The trick here is to use common sense and remain consistent.
The area to the left of the circle is your scene overview. Its the set up, any rules or observations, phases, perhaps even some read aloud text. The TotEM card at the top is representative for the whole space in the Circle. It's the greater location that the scene takes place in.
The area to the right of the circle is where you can add complexity to the scene. In the same way the best battle maps have verticality, interesting terrain features, phases — the TotEM system allows you to describe rooftops, entrances, balconies, caves, a wagon... whatever, as long as its fundamental to the scene you're trying to bring to life. You hide those that the players don't yet know about... like a secret entrance or a backroom and show those to allow players to make narratively tactical decisions.
I've had a couple arguments with fellow DMs about whether players can be tactical if there is no battle map, but I truly believe one can. For about the first 15 years of my roleplaying, there were precious few maps. Miniatures were lead, had to be imported from overseas and were damn expensive and were mostly humanoid for wargamers — but even so, players had to strategise and use team work in combat to overcome the games threats. It was deadlier in those days for players, they had to be tactical in their combat decisions.
Of course this isn't meant to replace Gridded Combat on Battle Maps or even Theatre of the Mind, each of those modes of play offer fantastic and different ways to enjoy the game. I love making battle maps and pouring as much detail as I can into them for my players and I love being surprised by a player to have to invent something on the spot only through narration.
Where these have been useful is if I don't have a map (or maps) with very specific features, or no time to make them, or no desire to include the micromanagement of movement in the encounter - I just want them to be able to get to where there are things to do. When you don't have the restrictions of having to use a map, but also don't have to rely entirely on the collective imagination at the table — the TotEM Circle can perhaps be the sweet spot between.
I've include one example, a jailbreak. A couple transparent pngs for you to overlay on whatever mood establishing background image you like and a black and white version.