Tech Review: The Mionix Castor Optical Gaming Mouse

(Photos by Jorge Figueiredo)

To many people, a PC mouse is a peripheral used to move the cursor on the screen and select things. To many gamers the input device is far more important. Choosing the right mouse can be the difference between success and failure, and the best mice manage to merge form with function. The Castor Optical Gaming Mouse is the latest offering from Mionix, and is a premium ergonomic piece of tech boasting comfort for all three major grip styles.

Castor 1

At first glance, the Mionix Castor is a fairly simple-looking mouse. The clean lines and a matte-black colour scheme can be underwhelming when compared to flashier mice on the market. However, closer study of the six-button mouse reveals a clever design with eye-catching elements that go well beyond electronics. When I review technology, I try to take a run at each device before reading the manuals to get an honest first impression with minimal bias and expectation. The Castor instantly felt comfortable thanks to indentations for the ring and pinky fingers that allow for a better grip with the multi-layer rubber coating. The surface texture is smooth yet non-slip even during moments of sweaty-palmed stress, and the shape of the Castor facilitates claw, palm, and fingertip styles (the Castor has dedicated grooves for the latter). These days, I rock a claw-type grip and I found it perfectly comfortable after hours of use.

The 2m-long braided cable (gold-plated USB 2.0 connector) is the other noticeable feature. The length is perfect for desktop action, giving you some play in all directions and a relatively tangle-free cord that doesn’t catch on anything.


The Castor feels surprisingly light,‎ making it easy to manipulate without causing undue fatigue. I had no issue after an hour or two (I even used it at work, which amounts to a fair amount of testing time). Button placement is ideal, and the action of each button is perfect. It doesn’t take too much pressure to activate each one, but they’re not easy to press accidentally. That’s particularly important when it comes to the thumb buttons, which are usually the most troublesome buttons on mice that have them. The Castor’s are beveled, and sit nicely on the inside right edge of the right thumb. The scroll wheel has a thick rubber “band” and is grooved to allow for maximum grip, while beneath the scroll wheel is the three-step Dots-Per-Inch adjustment button.

Castor 2

On the underside of the Castor is the IR-LED optical sensor, which has been cleverly made a part of the Mionix logo. On the top and bottom edges are two polytetrafluoroethylene (PTFE) feet. Both are large and span the width of the mouse, giving the unit a decent amount of “slipperiness” on practically any mouse-ready surface. The scroll wheel accents and the logo on the palm area of the mouse are backlit by LED lights. Each light is capable of displaying one of 16.8 million colours, which can be displayed as a single, solid colour or a patterned colour shift (for the record, colour-shift in a breathing pattern is most awesome). It doesn’t really affect the performance of the mouse, but it’s certainly a cool feature.

While the physical design is impressive, the stuff under the hood ends up stealing the show. Beneath the rubber and plastic, the Castor has a 32bit ARM Processor (running at 32Mhz) with 128 kb of memory, giving the mouse enough juice to handle any profile changes you throw at it, with no undue positive or negative hardware acceleration (meaning no outside interference – it’s only your movements that are captured).

The mouse is Plug-and-Play, so it doesn’t need anything other than the standard Windows mouse drivers (I run windows 8.1 64 Bit) if you don’t feel like getting fancy. The mouse will glow a solid default colour, and the three-step DPI button will work (though the default values may not suit everyone).


Castor Sensor Performance

To get the most out of the mouse, though, it’s a good idea to install the Castor software, available from Mionix’s website. The software runs in the background and is very easy to use, with a nicely laid out set of configuration screens. Using the software, you can configure basic settings (like double-click interval, acceleration, and button assignment), as well as more advanced settings (like lighting and sensor performance). If you need more precision, you can utilize Mionix’s signature Surface Quality Analyzer Tool (SQAT), which gives you a reading of your current surface to help you configure the amount of lift distance that the Castor can tolerate. Macros can also be recorded here, giving you access to keyboard and mouse commands that come in handy for real-time strategy games. It definitely works, though I tend not to use this feature.

Mionix indicates that the Castor’s limit is 10,000 DPI with a maximum tracking speed of 5.45 m/sec and a four-step adjustable polling rate (1000Hx max). To put the mouse through its paces, I tried a variety of different games and applications, including Battlefield 4 and Skyrim. The Castor was very responsive in both games, though I had to tweak it once or twice using the Castor software until I got it just right. Once configured, the settings stay active in the profiles stored in the mouse’s memory. Being able to switch between the different DPI settings is handy, especially in games that involve using a scope. It takes some getting used to – when I first started playing, I would glance side-long at my mouse fairly frequently – but once I had the optimum settings I seldom had to verify that the mouse was working properly.

In other games that require a different kind of accuracy (like Civilization V or Gathering Sky), the Castor performed just as well as it did in the first-person tests. Across all of the games, I found that the extra groves for my last fingers and the relatively light weight made it very comfortable and thus enabled me to play longer. Using the Castor for work also had some advantages. Aside from less fatigue and a high amount of precision, changing DPI is handy for those who spend time in CAD programs and drawing creation/manipulation.

Castor Color Settings

There isn’t much to complain about when it comes to the castor. Nitpickers will note that the rubber coating attracts dust quite easily (my photos were taken when the Castor was right out of the box on a clean surface). My only real issue is the lack of LED indicators for the DPI settings. I found that sometimes I got lost, forgetting which DPI setting I was in (which isn’t unreasonable considering some of the crazy situations in which I was switching DPIs). For those who prefer their DPI values closer together, I can’t even imagine how difficult it would be to tell where you are in the spectrum.


Fortunately, there are ways around the problem. A few clever users actually assigned a profile change to a button, taking advantage of the Castor’s ability to store 5 profiles. Each profile is given a different DPI value (all 3 DPIs are the same in each profile) and a distinct colour to keep track of them. However, it seems to be a bit of work, and you have to switch between 5 values rather than 3. A simple LED indicator (or perhaps tying the scroll wheel accent lighting to the DPI button) would circumvent the problem.

If you’re a gamer looking for a new mouse then the Castor might be a decent one to choose. Online retailers have been listing it between $69 and $79, so it’s not cheap, but the plethora of features make it worth the coin (the Mionix Castor ships with the mouse, a Quick Start Guide, and a sheet of stickers). Highly responsive and customizable, the Castor gives you an elegantly simple solution for games and work, and allows you to let your personality shine through (a little) with its dual lighting system. Though it is an awesome product, it might not be for everyone at first. If you are new to PC gaming, it can be intimidating and may take some getting used to. Once you do, you’ll find that it will enhance the way you play your games.

Castor 3

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