G502 comes in a really tiny box, containing only the mouse, the 60 page novel Logitech calls a manual, and the tuning weights and weight case.
Proteus Core is probably the flashiest mouse Logitech ever made. Its still down-played by gaming mice standards, but it does feature blue lights, sharp edges and polished surfaces, which are the mandatory and completely unnecessary additions to any gaming peripheral. It looks like a low-profile G602, with a plastic plate strapped to its side, some rubber added for a better grip, and an obligatory (but thankfully subtle) blue-light logo on its back.
Though it looks "gamery," the mouse feels great in hand, especially if you're a palm-grip user. The clicky action is fantastic, and the heavyweight metal scroll wheel (a considerable improvement over G602's rubbery wheel) uses a mechanical switch that allows you to toggle between notched and free-spinning (like G9X or G700) mode. Whilst I have no complaints over the free-spinning mode, I have a few complaints on Proteus' scroll wheel. First of, it feels kinda wobbly, so much so that moving the mouse around, you can sense it shake through the plastic. Also, when used in notched mode, the steps are so pronounced your finger might just slip off the wheel (that polished metal is not known for its adherence).
Turning the mouse around, one discovers a nicely textured underside. It looks similar to the G602: 2 large PTFE slippy pads, two smaller ones, and the sensor dead in the center, but Proteus Core has a customizable secret.
Remove the patterned cover surrounding the sensor, which is held close by a magnet, and you gain access to the heavily marketed weight tuning system.
Proteus Core features 5x3.6g weights that can be used to tune the rodent's balance and overall heft. I like me some heavy mice, but G502 is 128grams without anything added (it doesn't have any small metal slabs inside like Tt eSports Volos had), and 168 grams with all 5 slabs in position. It's slightly lighter than Volos, but that one had 3 metal plates screwed to its top-side for no reason whatsoever.
I tested the Proteus Core on multiple surfaces, including rough cloth pads like the SteelSeries QCK and QPAD UC or smooth ones such as Logitech G240 and Tt eSports Pyrrhus. As expected, Proteus Core's weight hampers its gliding action on rough surfaces, but there's no problem with smooth (& thin) pads. Tracking is the same across the board, and the software package allows you to tune the mouse to the surface you're using.
G502's sides are akin to those of its perma-wireless brethren, but with a number of improvements. First, an absolutely extraordinary patterned rubber coating adds some additional texture and grip, and instead of the 6 sharp-angled side-buttons G602 featured, it carries only two large ones (mapped to Back & Forward) as well as an obligatory Sniper switch.
On the right side, there's nothing to press, since the mouse is designed for right-handed users only.
As expected, the cable is heavily braided, though I feel the braids are slightly looser compared to other models, which means it's a lot more flexible than your standard cable. Thankfully, Logitech was also kind enough to include a hook and loop cable tie, and that's something we just don't see enough these days.
Proteus Core is similar to the G602, which was a very good palm-grip mouse, but not much else. However, I think Logitech designed this rodent trying to appeal to every grip-type out there.
I can't say they succeeded all the way through, but they came close. Left & Right click can be used from the back of the switch; the side-buttons are accessible to both claw and fingertip users (except the Sniper button, that one's exclusively for palm-grip users); and the low-profile makes it easy to get used to it.
However, if every user can get something out of it, that doesn't mean it's a perfect fit, quite the contrary. The mouse still has some heft behind it, and the overall shape and size, well it favors the heavy-handed.