How our game conquered all VR platforms

An exclusive Spatial News™ interview with Jaakko Asikainen, director and designer of MeKiwi's popular game Cave Digger

So tell me, why is Jaakko Asikainen?

I'm an old school gamer and love everything about them. When life dropped me out of the IT circuit, I put my money where my mouth was and started making games, mostly doing design and direction nowadays.

For the readers that might not be familiar with Cave Digger, please describe the game and how it got its start.

Cave Digger was my first VR game and I love it, warts and all. It all started in November 2017 with pre-production for a demo of Cave Digger. From the beginning, we used Virtual Reality Toolkit (VRTK), which allowed us to quickly get going with basic VR mechanics like teleporting and grabbing. We didn’t know it at the time but using VRTK was a boon for porting as well. Anyway, we released the demo on Steam in May 2018 to gauge the need for such a game.

So what do you think is the appeal for a game like Cave Digger?

There is something oddly satisfying about hunting for loot. Hack at the rocks, get the shinies inside, and buy stuff. Indentured capitalism or primal satisfaction in revealing a hidden thing? Who knows really. It’s just a fun game.

When did you know that you struck gold with Cave Digger?

The demo got more than 100k downloads on Steam. So we started to make a commercial version - Cave Digger: Riches.

What was different from the demo version?

We added 4 more alternative endings, more level and loot types and also released the game on both Oculus and Viveport. When we ported the SteamVR build to Oculus Rift and PSVR, it made things so much simpler, just plop the SDK in and you have the basic mechanics working. Not that everything was rosy though. The problems in VRTK’s own development made us fork a version of our own which included some later VRTK fixes. Also, the VRTK SDK for PSVR had lots of problems that we ended up fixing and sharing with the community.

When did you release the PSVR version?

We released it in March 2019. It took about half a year to go through the Sony submission process, gaining some nice experience for the future.

You said that you also released the game on Oculus. How did that go? What kinds of adjustments did you have to make for that platform?

In 2019 Oculus approached us to bring the game to Oculus Quest. This was excellent. Not only could we release the game on Quest but we also had the resources to create lots more content. This became known as the "Train Update", which we released for free for all owners on all platforms. Back then we had Steam, Oculus, VivePort, PSVR, and WMR (Windows Mixed Reality) builds, basically everything using the same branch and the same scene.

One scene was all we had, and it was filled to the brim! In the final train level, we were so far from the 0,0,0 point that we saw visible floating-point errors, but minor glitches can be tolerated as long as the soul is there. The Quest porting was the real challenge. With the game optimized for PCVR, we had a real problem on our hands - how to get it to run and also look good on the Quest. We had to reduce draw call counts from 1000+ to 150, vertex counts from a million to 200k and optimizes CPU load to have the game running at constant 72fps. We did it in 4 months, all the while fixing more than 500 QA tickets. That was a real war of attrition, but we won in the end.

Ok, so you had Cave Digger on 5 platforms. Any others?

After Quest, we had also done porting for emerging Chinese VR platforms - Pico Neo 2 and Nolo X1. These were easy enough since we did the legwork on Quest. Having conquered all the VR platforms, we decided to bring the VR-exclusive experience to all gamers.

What made you decide to create a flatscreen version of Cave Digger?

The fans asked for it basically. Also, as we're into publishing as well, I thought it would be useful to have releasing experience on all the possible platforms.

What were some challenges of transforming a VR-exclusive game into flatscreen?

What started as a minor side project turned out to be a real handful. The controls, the UI, the 1st person view, the animations - all had to be re-designed. We avoided changes to the content and concentrated on the actual first person experience. Of course, we needed to add some basic FPS mechanics like running, jumping, and crouching. Since VRTK was so deeply ingrained in the game, we ended up cloning the VRTK Simulator mode and creating a separate First Person SDK based on it. This way we didn’t have to separate the two games fully and fixes for the VR version benefited the flat version and vice versa. Another thing we added was controller support. This was naturally a must for PS4 but we also wanted to support all the possible controllers on PC. For this, we used a handy Unity3D plugin called InControl.

Thanks for the breakdown. I think this could be very helpful to those thinking of bringing their VR games to flatscreen. When was that version released?

The flat Cave Digger was released on Steam and PlayStation 4 on August 14th. Players are picking up the game, giving feedback, and participating in further development.

You have VR Digger released on 7 different storefronts (Steam, Oculus, VivePort, Windows Store, PSVR, Pico Neo 2, and Nolo) and the flat Digger is released on Steam, PS4 and now also PC/flatscreen. What’s next?

Xbox and Switch, naturally. Once those are done, I don’t think there’s another game released on so many platforms. Maybe, Tetris.

That’s very impressive. I heard that someone put Doom on a digital pregnancy test. Will you accept the challenge?

We were joking about a mobile version actually. But we're not going to go there.

Anything else you'd like to share?

We have some very big news coming. Join us on Discord http://discord.gg/cavedigger and stay tuned!

Thanks for taking the time to talk with Spatial News™, Jaakko. Have fun storming the castles!