History
CALIBER.50 is a top-down, multi-directional shooting arcade game set during the Vietnam War in 1972. The game itself was developed by SETA, a company that at the time frequently worked as a subcontractor for Taito’s arcade titles. In the game, the player controls a captured U.S. Air Force pilot who must escape from an enemy prisoner-of-war camp and fight his way through the jungle. One of the most distinctive features of the game is the overwhelming number of enemies. It is a bullet-hell game but with soldiers! They appear relentlessly and from all directions, attacking the player from a full 360 degrees. Their appearance patterns are not fixed, which creates a constant sense of unpredictability and pressure.
The graphics are particularly impressive. The lush green jungle is beautifully rendered, and there are many small details in the animations and effects. For example, defeated enemies fall in several different ways, some enemies burst into flames and vanish instantly when hit, and even environmental details are animated: if a bullet hits a turtle in the river, its shell flips as if it has died, only to slowly return to its original position. These kinds of subtle visual touches make the game’s presentation especially rich and immersive.
The Core
This core started by a PCB donation from Kristian Hall. It looked like a simple enough game: the usual Motorola 68000 paired with a 8-bit CPU for sound. I did not know at the time we were in for a ride! First, the 8-bit CPU was a variation that was not correctly implemented in the open source community. So I had to make my own. The sound chip was not the usual Yamaha but a custom one, which required a lot of work too. Then, the graphics chip were a mix of those in The New Zealand Story and a new one. I thought I was going to be able to reuse the ones from the NZStory core at least, but they were using new configuration bits unused in the other games, which require some investigation.
The board schematics were done by Skutis and he found a very interesting sound feature. The game uses the left and sound channels of the PCM chip to play sounds at different sampling rates, which require different antialiasing filters. The two channels and then merged for a clean if mono output
Overall, it took much more effort than anticipated. This beta still has occasional GFX and sound glitches, but they do not get in the way and it is fully playable. The game works with a rotary stick. If you do not have, you can use extra gamepad buttons to turn the player around. As a rotary stick game, it is briliant, very enjoyable.
Other Updates
Fixed Score broken in Renegade and Nekketsu Koha Kunio-kun
Supported 5-button inputs in the hidden secret menu of Tenchi wo Kurau II
Fixed coin buttons not working in Warriors of Fate
The NeoGeo Pocket game saving feature is now working in most games, but Metal Slug fails and that is driving the team nuts. This feature is still not ready for release.
Engaging in more time consuming tasks and cores is actually hurting the number of subscribers. I am considering doing a few weeks of easy cores to bring more life to the Patreon page. We are also planning to cover more arcade content on Patreon too, not just purely the FPGA core. You will see more about this soon.
Thanks for your support!