So, I know generic traversing upgrades include things like being able to jump twice, or flight, or the ability to climb walls. However one that I feel is rarely used that is actually a very fun ability to play around with are ones that allow you to tether to a point, and swing around or pull you to things. I'm thinking of something like the whips from "Secret of Mana" and "Castlevania", and the Grapple Beam from the "Metroid" series put together. I think this would be something that would be easy to introduce, perhaps hard to code, but overall a fun addition to a game that is looking pretty damn good.
My ideas for this upgrade would be for not only traversing, but also puzzle solving as well, giving it the ability to pull certain objects to you. For example, perhaps pulling a heavy block that can't be pushed so that it remains on a pressure switch to open a gate.
Anyways, let me know what you guys think, also since I have to give it a name, I think I would call it the "Chain Whip".