Dennis Debro Shares His Experience Working on Yars' Return

Dennis Debro Shares His Experience Working on Yars' Return
The team at Atari recently asked Dennis Debro some questions about the development of Yars' Return. Dennis Debro worked with Curt Vendel on the development of the Yars’ Return. He also contributed to the Atari XP release, digging into the code to make some refinements.

Q: How did you get involved with the development of Yars’ Return?

DD: Curt Vendel and his team at Legacy Engineering had a contract with Atari to produce the Atari Flashback 2. I worked on the game Atari Climber, one of the 40 games initially available on the Atari Flashback 2. I was excited to see the unit released. Curt had worked with Atari before, and being an enthusiast, was able to convince them to release this unit. To me, this was almost like releasing the Atari 2600 again. Having an Atari 2600 was a magical time for me as a kid. Seeing this unit coming to market was almost like recapturing that excitement.

When the original units were released, I wasn’t pleased with the outcome of Yars’ Return. The original game was so buggy that it was unplayable. I reached out to Curt and voiced my opinion. I really wanted better for his work. We communicated more about this for a couple of weeks I believe. Curt sent me the final ROM for Yars’ Return and asked if I could fix it. He didn’t have original source code so I reverse engineered the ROM producing workable 6502 ASM source code. Once I fixed the game to where it was playable, Curt asked if more of his vision could be added. We then worked together to produce a working copy of Yars’ Return that fit his original vision. 

Q: You are a fan of Howard Scott Warshaw’s Yar’s Revenge. What about the title appeals to you?

DD: I’m a fan of Howard Scott Warshaw! If we are to target Yars’ Revenge then that’s a really good question. I focused more on playing Ultimate Yars! I loved the intense battle with the Qotile. The game ramps up well. Just when you think you have the mechanics down, the Qotile gets more aggressive and starts chasing Yar! 

As a kid, I saw this as an original title versus an arcade copy. Later as an adult, I would learn it was Howard’s interpretation of Star Castle. Star Castle was an arcade game in the 80s and Atari had secured a license to produce it for their home consoles. Howard was tasked with creating this for the Atari 2600. Instead, Howard took what made Star Castle great, added the Howard Scott Warshaw touch, and we got Yars’ Revenge!

As someone that has written code for the Atari 2600, I have a newfound respect for the title. This is a great product / title for Howard to have as his first title for the Atari 2600. He was able to get all this action done in a game that is 4K in size and only 128 bytes of RAM. With that finite amount of space, there are some tradeoffs that must be made. He solved one very well by using the actual game code as the graphics for the Neutral Zone.

Q: We understand there is a twist on the easter egg in this title?

DD: The original release of Yars’ Return had an Easter Egg that was really only supposed to be used as a joke for the playtesters. Unfortunately, that Easter Egg made it into production. Once I was aware of the mishap, I immediately contacted Howard to let him know.

The original Yars’ Revenge has an Easter Egg that will produce Howard Scott Warshaw’s initials when triggered. In the one I made for the playtesters, I had replaced this with my name ending in a smiley face emoji as a joke. I felt awful that this made it into production. Yars’ Revenge was Howard’s creation. I didn’t want to take from that.

Once I alerted Howard, he immediately responded that he understood and took no offense. I was glad to hear that. I did not want to offend him or take away from his legacy in any way. He then proceeded to send me autographed copies of his book Conquering College: The Most Fun You Can Have Learning the Things You Need To Know for some future high school graduates in my family. Thank you Howard!

Q: Is there a backstory on the apostrophe in the game title?

DD: The original is titled “Yars’ Revenge”. With the hero being named Yar in the manual; wouldn’t that mean the entire Yar species is seeking revenge? For the original release on the Flashback 2 unit, I don’t think anyone caught this prior to going to production so the game there was titled “Yar’s Return”.

Q: Can you tell us about your work on the Atari XP version of Yars’ Return? What improvements have you been able to make in this latest release?

DD: There were a couple of bugs in the release we did after the original Flashback 2 units. One was spotted after release where only one of the two Destroyer Missiles would actually harm Yar. Another would only be found in sensitive 2600 units. I hope I’m not getting too technical, but it had to do with the way I was manipulating the 6502 stack. I was able to find this thanks to the wonderful team developing the Stella emulator.

Another item that was improved would be the Shield graphic. The Shield is now a solid graphic instead of being interlaced as before. I learned a lot more about coding the Atari 2600 since 2005. 

A proper title screen has been added as well. Now the game will display the game selection names instead of game selection numbers. This was a limitation in the original Yars’ Revenge given it was done in only 4K of coding space. Yars’ Return was expanded to 8K of coding space and I had the time so, why not.

The Easter Egg was also changed. The Easter Egg, in my opinion, now gives proper credit. It also allows the player to continue their game once triggered. A feature I wanted in Yars’ Revenge.

Q: You have been active in the home brew community. What is it about 8-bit game design that appeals to you?

Atari 800 Computer

DD: I grew up on the 6502 with an Atari 2600 and later with an Atari 8-bit computer. It’s nice being able to memorize the entire instruction set  in your head. Specifically for the Atari 2600, I love the tricks needed to get the Atari 2600 to do what you need it to do. This unit was originally developed to do two games, Tank and Pong. The game engineers took this vision so much further. They have produced games and utilities that the original designers never envisioned for the unit. Fast forward roughly 40 to 45 years later and the kids that grew up with this unit in their living rooms and bedrooms have now started to write for it. 40+ years later, we are still discovering new things that can be done with the 2600.  

Q: Anything else you would like to share?

DD: Yes, I want to thank Curt Vendel for allowing me to join his Flashback 2 team back in 2005. The reason Yars’ Return exists is because of Curt. Curt loved Yars’ Revenge and wanted a sequel with the Flashback 2 unit. Yars’ Return is Curt’s vision of what that sequel would have been.  Curt has done so much for this community. A lot of the Atari historical documents we have today are because of his efforts.