Mionix Castor review: an expertly crafted gaming mouse

Mice, Peripherals, Reviews


Mionix is well known in the gaming world for their lines of Saiph and Naos mice, but their latest model is the Castor. The Castor combines a right-handed ergonomic design with a zero-acceleration optical sensor and Aurora RGB backlighting. The mouse is in stores today, so let’s see how this new mouse fares!

Features & Specifications

  • PMW-3310 optical sensor, max 10,000 DPI, no hardware acceleration
  • Right handed truly ergonomic design, supports palm, claw and fingertip grip with 4-layer soft touch rubber coating
  • 6 fully programmable buttons, 3 steps in-game DPI adjustment
  • 2 integrated RGB LEDs in 2 colour zones, 5 effects
  • 32-bit ARM processor at 32 Mhz, 128 kb built-in memory
  • Gold-plated USB connector and 2m PVC cable
  • 122 x 70 x 40 mm, 93.8 grams (w/o cable)

For additional features and specifications, please visit the Mionix Castor product page.



The Castor comes in a cool box that opens diagonally, revealing an inner inscription: “Congratulations! You have purchased a fine piece of craftsmanship.”


This is followed by the obligatory hashtag: #MIONIXCASTOR. Another famous saying comes on the silica gel packet inside the box: “Do not eat.”



The Castor has a refined, streamlined look, with side buttons on the left and a subtle bulge on the right to better accommodate right-handed gamers. The mouse is largely wrought of soft touch rubber, giving a grippy and comfortable feel.


Besides the fourth and fifth buttons, the left side also includes a textured thumb grip. The right side of the mouse is bereft of further features.


The Mionix logo and scroll wheel are RGB backlit, changeable to 16.8m colour options in the software. A button below the scroll wheel allows DPI changes, moving between three DPI levels defined in the software.


The bottom of the mouse is spartan, with only the optical sensor, a pair of large skates and a message: “Mionix – it’s all about the craftmanship.”


The 2 metre cable is clad in a PVC sleeve and ends in a gold-plated USB connector.


The mouse is relatively small and light compared to past Mionix mice, which should make for greater maneuverability and easier lifts.


Screenshot 2015-09-02 13.32.30

While the Castor works fine out of the box, you’ll likely want to install Mionix’s software package in order to customise its looks and performance.

Screenshot 2015-09-02 13.32.32

This software is fairly standard, offering a means to alter the DPI settings and remap each button, whether you’d like to rebind it to a keyboard button, a complex macro or something in between.

Screenshot 2015-09-02 13.32.34

You can also customise the look of your Castor by choosing the colour of each backlight.

Screenshot 2015-09-02 13.34.30

The Surface Quality Analyzer Tool seeks to quantify the performance on your chosen mousing surface, whether that’s your desk or a mousepad. It seems fairly accurate, and a good way to choose the best mousing surface available.

Screenshot 2015-09-02 13.35.23

The final page of the software offers help, product registration and downloads – very useful.

Screenshot 2015-09-02 13.34.33


In order to see how the Castor performs for its £60 price point, we tested it in a range of recent games as well as day-to-day web surfing, photo editing and general use. Here are some of the titles that we tried with the Castor:

Counter-Strike: GO StarCraft II Civilization V Call of Duty: Black Ops III

The first test for any gaming mouse for me is Counter-Strike: Global Offensive. This game requires a lot of accurate mouse movement, both subtle shifts for long-range shots and rapid movements for checking corners when entering a bomb site. The default sensitivities were very high, but after setting these to more appropriate levels I had no issues. The Castor felt right at home in my hand; I was able to jump straight into competitive matchmaking without any worries – unusual for a new mouse.

2015-09-03 03.45.00

The refined shape was immediately comfortable for claw or palm grips; I don’t really use tip grips with any regularity so I can’t speak to the mouse’s efficacy here. The light weight was also helpful, letting me move the mouse the width of my mousepad without growing weary. The textured left side of the mouse was particularly handy, adding grip without forcing the mouse into an odd shape. I wish we could see the same on the right side of the mouse as well.

For more sedate fare like Civilization V, the relatively small body of the mouse was a little less comfortable than wider alternatives, but still perfectly fine for a brief two hour session.

Moving to StarCraft II again put more demand on mousing accuracy, and I again found the Castor to be up to the task. I like having a couple of control groups on my thumb, and the two left buttons allowed me to do so without stretching. These can be remapped to either single keyboard keys or macros; for the latter I found recording to be easy but editing to be hard. It wasn’t possible to edit delay en masse, which was a pain when recording a longer macro.

2015-09-03 03.45.26

The last consideration is style – is this a mouse that will turn heads when I turn up at the LAN? Not really – the design is refined and streamlined, but at first glance the Castor doesn’t look noticeably different to other Mionix mice, with the same shape, logo placement and materials. Mionix could do more here to make a stand-out mouse, perhaps investigating different materials or colour schmes to set themselves apart from the legions of boring black mice on the market. Once nice addition was the RGB backlighting, which allows you to at match colours with your other LED-lit peripherals like keyboards and headsets.

My general expectation is that any high-grade gaming gear should work well enough in non-gaming use too. With its comfortable body and accurate sensor, the Castor was 90% of the way there already. The only minor complaint I had regarded the scroll wheel, which lacked tactile, clicky feedback compared to the divine G700S. It was also a little slow by default, but bumping up the sensitivity did the trick. Whether web browsing or doing Photoshop, the Castor was an instant replacement for my usual SteelSeries Sensei.


The Mionix Castor is an excellent gaming mouse, with a simple appearance that belies its well-considered design, premium construction and excellent components. While some may prefer flashier gaming rodents, I can certainly respect Mionix’s gimmick-free ethos. Now – bring on some special editions in cool colours or interesting materials, and we’ll have a real 10 / 10 candidate for sure!


  • Comfortable and ergonomic, suitable for long play sessions
  • Light and maneuverable in a range of grip styles
  • Solidly made, with no useless gimmicks
  • No-acceleration optical sensor is reliably accurate
  • Sensible, bug-free software


  • The grippy left pad attracts dust and fluff with speed
  • Overall look is very similar to past Mionix designs, a bit boring




Last modified: September 3, 2015

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4 Responses to :
Mionix Castor review: an expertly crafted gaming mouse

  1. Night Waddle says:

    A “boring design” is a petty thing to be a con and is very opinionated. If a design is working for them, there’s no reason to fix what isn’t broken. In my opinion, the new design is exciting. They do use the same materials, but the shape is new, taking some hints from past designs.

    1. William Judd says:

      This whole review is my opinion, right? :) I’d personally like to see something more novel from them, something that stands out on a desk and is instantly recognisable as different from their past efforts. I think they have the design chops to do it, even if it doesn’t become their main mouse. In any case, I’m glad you like the design.

      1. Night Waddle says:

        I thought the rest of the review was great haha just when I was looking over the bullet points on pros and cons I thought it was strange that “boring design” would be considered a con. Their rubber coating with that LED logo is sort of their signature design.

        1. William Judd says:

          I really like peripherals that stand out against the crowd, with shape, colours or materials. When you rock up to a LAN, it’s great to have people ask “Whoa! What’s that thing?!” Some mice – like the Cougar 700M, for instance – have that stand-out quality in spades; others like the Castor lack it. That’s why I list it as a con, and I trust that my readers that don’t care about appearance will discard that observation.

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