Cursed Technique Idea: Wormhole
This cursed technique would probably classify someone as Grade 1 automatically, as while it is not very destructive, and its application is very limited, it is an extremely strange and versatile technique, and requires a hefty amount of cursed energy to be used repeatedly.
As of now, I've thought of a lapse technique, a reversal technique, and a domain.
Lapse Technique: Tunneling
The user, upon picking a visible destination of any distance is able to fold space like a sheet of paper, and punch a hole through spacetime, to near instantly cross the distance and physically walk to the destination. It essentially functions like a portal, but rather than creating a physical, lasting portal like in the games, the user instead sees reality fold inward until the destination appears to be physically in front of them or mere walking distance. When crossing the wormhole, they would move as though they were still in the 3 dimensional world. Being able to effectively apply this technique in battle requires a heavy cursed energy reserve, as well as a very good understanding of angles, positional awareness, and physics. The user can punch wormholes in any direction, to any destination, so long as they can physically see it. Tunnels CANNOT form if they touch any physical object, they can only manifest in open air.
Opponent Interaction
From an outsider POV, upon Tunneling being used, the user would essentially walk forward, and then disappear as if they had walked into an invisible door, and just as quickly exit from a completely different displacement. The opponent can also interact with the wormhole, though they cannot see spacetime fold, if they have a keen eye and are good at sensing cursed energy, they will notice a visual disturbance in spacetime wherever the user is about to exit the wormhole and they will also sense the users cursed energy from that direction. If they are capable of predicting where the opponent will exit, and are fast enough, they can travel through the wormhole themselves and attack the user before they even have a chance to go through the tunnel. However, this is EXTREMELY RISKY, as the user can close the wormhole before the opponent has finished moving through, resulting in the traveling opponent being sliced apart by space-time a la World Cutting Slash. However, due to the limitations on where the wormholes can be created, the user cannot suddenly spawn a wormhole around the torso of the opponent and then close it to slice them in half instantly, meaning getting portal sliced is not a serious risk unless you are incompetent enough to go through one while it closes.
Reversal Technique: Hole
Physics manipulation technique to ensure a target never reaches their destination. Much in the same way that Infinity reduces any change in displacement towards Gojo's body into an asymptotic x^-1 function, invocation of Reversal Technique: Hole, allows the user to designate two targets, and renders the displacement function between the targets (usually themselves and their opponent) (X^2)/X. The targets can still move unrestricted, but if they try to physically interact with the other target, they will be stopped by spacetime itself. It essentially functions as an automatic deescalation tool. Hole rapidly burns through positive energy that could otherwise be used for RCT, so if the user decides to invoke it, they better have a plan on how to stop the fight permanently.
Domain Expansion: Tesseract
This domain expansion forces those within the barrier to experience the physics based distortions that the user is able to create, but on steroids, and completely outside of their control. The physical environment is a massive, constantly-folding 4D supercube (SEE IMAGE). While inside this supercube, the sure-hit technique is known as the "Omni-Directional Fall". The victim is now constantly falling down, but from basically any direction. As soon as they hit the border of the cube, the reemerge from a completely different section of the cubes border, and fall in a completely different direction, but they are always accelerating. Air resistance does not exist (though everyone can breathe) and the only limit is the speed of light. They are unable to gain any sense of direction, positional awareness, or ability to stop falling or change what direction they're going. They can only move their body and try to block whatever attacks are thrown at them. The user is free to move omni-directionally at any speed, and can strike the constantly free-falling opponents at will. Either the opponent is killed inside the domain, or the domain is broken, and the opponent flies out of it at whatever speed they were at and potentially ends up a splat on the side of a building. If they have built enough velocity and momentum and fly upward, they could even potentially get launched off the surface of the planet (but they would have to be falling for a long time).