One of the most effective ways to execute an intense cardio workout in a short amount of time is with High-Intensity Interval Training or HIIT. Generally, these intersperse periods of movement conducted at maximum exertion for a short period of time, usually 30 seconds to a minute, alternated with a rest period, usually 30 to 90 seconds, for multiple intervals lasting anywhere from 15-30 minutes. A subset of HIIT, called Tabata intervals or “Tabatas,” are popular with Crossfitters and are known for being especially effective and especially grueling.

Bitslap from developer Comrex AG ($6.99 on Steam), much to my surprise, very closely resembles the structure of Tabatas, which alternate 20-second work intervals with 10 second rest periods for a total of 4 minutes. The main difference between the two is that a single round of high-speed Bitslap lasts around 2 minutes and that it’s predominantly upper body, but by doing two rounds in quick succession, you can replicate Tabatas to great effect.

Bitslap embodies the notion of “simple but not easy” to devastating effect. In normal mode, which is what I used for this review, two cubes will spawn in front of you in sequential order. Strike the cubes in the order they appear, and a new cube will spawn as quickly as you can strike down the last one. If you hit the cubes out of sequence, there is a penalty to your score, and you have to course-correct your hit pattern to progress. Perhaps best of all, Bitslap can put you into a “zone” where you are purely reacting faster than you have time to think about reacting. It looks like this.

Intensity – 10/10

This is absolutely the most intense game I’ve played in VR, but as in most things VR, your mileage may vary. There’s a bit of a skill curve where your conscious mind will try to keep track of the cubes as they manifest, but once you stop thinking about which cube to hit and you fall back on instinct, your fists just take over. Once in “the zone,” you’ll be punching as fast as you possibly can limited only by your ability and your muscular fatigue. By the end of my one-hour play session, I was completely smoked.

Calories burned : 823 cals. in 62 minutes (13.3 cals/min)

: 823 cals. in 62 minutes (13.3 cals/min) Average heart rate: 147 bpm (79% of my max heart rate)

147 bpm (79% of my max heart rate) Max heart rate: 186 bpm (100% of max heart rate)

Arms – 10/10

Bitslap pushed my arms to their limits again and again. After a few rounds, they felt 10 pounds heavier and were like punching through quicksand. Compared to my first round, you can see how the fatigue creeps in as I move much more slowly and make more mistakes.

Legs – 6/10

This isn’t a leg game by any means, but I relied on my hips and legs to generate speed and force more than my arms alone could deliver. Taking a wide stance helped to generate force in all directions, both high and low.

Core/Balance – 8/10

For maximum speed, you’ll be pulling your elbows back as quickly as you are punching your fists forward. A strong core is needed to anchor your body while the constant push and pull of your arms in all directions threatens to knock your body off balance. You can see in this slowed down clip how hard my core and legs are engaged to both generate and overcome the force from my arms at high velocity.

Time Perception – 8/10

Once that state of pure action and reaction is achieved, the thinking mind goes away completely and time stands still. However, in between rounds and waves, the mind comes roaring right back again – and potentially in rebellion of your efforts – as you catch your breath and recover your stamina. An hour of this game is pretty demanding to accomplish, and it’s more suitable for shorter sessions of 15-30 minutes.

Perceived Exertion – 9/10

This game is strenuous, and you’ll be feeling every inch of it. That said, I can’t imagine replicating the speed and duration of these waves without the aid of VR. It definitely enables me to push myself harder and faster than what I’d be capable of just punching the air.

Fitness Scalability – 10/10

Bitslap automatically and dynamically adjusts itself to your ability. The game can be played at any speed, from very slow to lightning fast. One critical suggestion I’d make to get the most out of Bitslap is to turn the brightness all the way down in the settings menu. The game has a somewhat irritating feature where the further you progress without mistakenly hitting the wrong cube, the brighter the hue of the cubes becomes, eventually creating a giant blob of white light where it becomes very difficult to differentiate their location. Luckily this can, and should, be turned off.

Minimal Pauses in Action – 10/10

There is very little downtime between waves, literally ten seconds (or less if you skip ahead), and a game can be ended, and the next round initiated with just a couple swipes from your controller.

Enjoyment – 6/10

Bitslap is not enjoyable in the strictest sense of the word, but the effect of being in “the zone” feels very cool, and there is a great sense of accomplishment when you get through an entire wave without any missteps. That sense of accomplishment is however offset by the acute feeling of exhaustion and the understanding that the next wave is mere seconds away.

Replayability – 7/10

One playthrough of this game in normal mode and you’ve basically experienced everything it has to offer, although there are harder game modes – with more cubes – that can be unlocked after hitting certain milestones. What makes Bitslap replayable for me are how effective short bursts of it are for my training and then seeing how my skills improve over time. As your name rises in the leaderboards time after time, this fact becomes apparent. This game dramatically enhances your speed, focus, accuracy, and recovery the more you play it and with real-world carryover.

Lack of Nausea – 6/10

A downside of this game is not that it gives motion sickness, but that the environment is staged in the vacuum of space. If you have a fear of heights (even in VR) this game will make you uncomfortable. Turning on permanent chaperone bounds could help dispel this sensation if you are prone to it, but Bitslap could really benefit from some different environments. Not to mention, the discomfort of total systemic fatigue, but that’s a feature, not a bug!

Social and Competition – 8/10

There’s no multiplayer component, but there is both a local and worldwide leaderboard for you to compete against.

VR Fitness Insider’s VR FIT Score – 10/10

Despite a few shortcomings, namely the enjoyment factor and the discomfort of being in space, this game gets a 10 from me. No question, Bitslap can take your VR workouts to another level I’ve not experienced in any other game, and all in a fraction of the time. With its HIIT structure, Bitslap can accomplish aerobically in 20 minutes what takes an entire hour in many other VR games. Also, Bitslap’s capacity to dynamically scale to your ability means that with dedication it can take your punching (or stabbing) speed to its full genetic potential, just like Ip Man.