In good ASUS tradition, despite nominally being its direct successor, the shape of the Keris II Ace has little in common with the original Keris, with the only shared trait being "right-handed ergonomic." Whereas the first Keris had a rather unusual shape, the Keris II Ace plays things much safer, and closely falls in line with the Zowie EC2 shape archetype. Innovation can be found in the structural design, as much like the Harpe Ace Aim Lab Edition, the Keris II Ace utilizes a bio-based nylon shell. The result of this effort is a mouse that is sturdy yet very light at 54 g, matching the LAMZU Thorn in this regard, which is similarly sized yet utilizes an open-bottom design. On my sample, there is no creaking or flexing of the shell when applying lateral pressure, and actuating the side buttons by pressing below them is impossible. The only build-related flaw I could find is a minor rattle coming from the main buttons when shaking, though this is wholly unnoticeable unless actively looking for it.

Though the Keris II Ace isn't the first ASUS mouse coming with optical switches for the main buttons (that title goes to the ROG Gladius III/Wireless), it is the first one having them by default. The main benefit for the customer is the fact that optical switches do not physically degrade the way mechanical switches do, which is why eventual double-clicking is inherently impossible. At the same time, optical switches will typically result in a duller, more muted button response, and that is the case on the Keris II Ace as well, and the fact that pre and post-travel are moderate doesn't exactly help in this regard. The button design is good, however, as lateral button movement is low even when provoked, and those who found the main buttons of the Harpe Ace too stiff will also be pleased to learn that actuation of these is a bit lighter. For the side buttons, ASUS has opted for surface-mounted switches from Kailh, and remarkably, these have essentially no post-travel, but some pre-travel at least. Since each switch is much smaller compared to a regular full-size mechanical switch, feedback is a bit lacking and not quite as satisfying, though the actuation point at least is even across the entirety of these. The scroll wheel encoder comes from TTC ("Gold"), and is known to vary wildly in terms of its characteristics. On the Keris II Ace, noise levels are under control, but tactility is average at best, as the individual steps lack sufficient separation. The feet are of the same triangle-shaped type seen on the Harpe Ace and other ASUS mouse releases, made of pure PTFE, and glide very well. A replacement set being included in the box is an added bonus.

Previous ASUS wireless mice have all been limited to a maximum polling rate of 1000 Hz in wireless operation, by virtue of being USB full-speed devices. While the Keris II Ace continues to be a USB full-speed device, ASUS's so-called Polling Rate Booster can be used to effectively transform it into a USB high-speed device, allowing polling rates of up to 8000 Hz in wired operation and up to 4000 Hz in wireless operation. The main benefit of this approach is that unlike the Razer Viper V3 Pro, for instance, the Keris II Ace still only requires a regular, small-size wireless dongle, so for those cases where higher polling rates aren't needed (e.g., travel), the Keris II Ace can be operated easier. Inevitably, the Polling Rate Booster adds a bit of overhead, but this stays well below 100 μs at any point, and thus may be considered negligible. The Keris II Ace also debuts ASUS's latest AimPoint Pro sensor, which goes all the way up to a whopping 42,000 CPI. As is customary with most recent ASUS mice releases, CPI accuracy is perfect on the Keris II Ace. General tracking likewise is excellent, owing to MotionSync being permanently enabled, ensuring consistent SPI reads in the process. Polling stability is another strong suit of the Keris II Ace—regardless of wired or wireless, 125 or 8000 Hz, polling is stable throughout. In terms of motion delay, the Keris II Ace delivers a bit of a mixed bag. For both wired and wireless, 1000 Hz underperforms slightly compared to most competitors, landing at 1 ms (wired) and 1.5 ms (wireless) relative to the Logitech G403 (control subject). In addition, certain polling rates underperform relative to others, too—for instance, 4000 Hz in wired mode is around 3 ms behind the G403, whereas 2000 Hz is 0.7 ms ahead. This makes picking a polling rate a little less straightforward than it should be, though aside from 4000 Hz wired, they'll all land roughly within 2 ms of each other, so the difference isn't huge. For click latency, the picture is much simpler: in wired operation, click latency will in the 0.3–0.4 ms range regardless of polling rate, and in wireless operation, 0.5 ms are averaged regardless of polling rate. As such, the Keris II Ace is on par with the competition from Razer, Finalmouse, or CHERRY XTRFY.

ASUS cites up to 107 hours of battery life, presumably at 1000 Hz. Though the software has a percentage-based battery life indicator with seemingly single-digit precision, I'm not sure how accurate it is, as the readings I was getting seemed almost too good to be true. Either way, at least 100 hours realistically can be expected without illumination, and the numbers using Bluetooth will be even better. Charging is also a pleasant experience on the Keris II Ace, as the current is reasonably high, and the charging cable plenty flexible, so playing while charging is perfectly possible.

Historically, ASUS mice have been good on the hardware side for many years now, but Armoury Crate has quickly become the bane of these otherwise worthwhile products. Aside from being a resource hog, Armoury Crate also tends to simply not work half of the time, and even mundane tasks such as installing and uninstalling quickly turn into projects. In an effort to at least reduce the Armoury Crate burden, ASUS has devised Armoury Crate Gear, which is a stripped-down installer package specifically for peripherals. For each mouse, a separate installer has to be downloaded, which functionally is largely the same as the Armoury Crate one, just without all the non-peripheral bloat. Though undoubtedly less intrusive than Armoury Crate, Armoury Crate Gear still spawns a non-negligible number of background processes, which occupy roughly the same amount of RAM, too. At least the processes of installing and uninstalling are more convenient, however, and I've found it to be less error-prone than the full Armoury Crate, too. Of note in this regard is also the ability to adjust polling rate and lift-off distance using button combinations, along with using the scroll wheel to modify CPI values, so going with Armoury Crate of any kind altogether is very much possible.

At $159.99, the Keris II Ace sure is no bargain, though at least in line with the competition from Logitech (Pro X Superlight 2) and Razer (Viper V3 Pro), and neither of these offer polling rates above 1000 Hz in wired operation. In terms of feature set, the direct competitor for the Keris II Ace is the Glorious Model D 2 Pro 8K/4KHz Edition, which is a decent bit heavier and larger, more affordable at $129.99, but cannot compete when it comes to performance. Overall, while not necessarily standing out in anything, the Keris II Ace is a competent release, and earns our Recommended award.