If you made all your games universal, I would have 100s of dollars in aspyr games on my G5. And don't tell me that "it isn't fast enough", I've heard that BS way to many times, I don't care if I get 5FPS, if that is obtained with out any form of the mess x86 is, and a lot of people are like me.
Feral kept supporting PPC until the number of PPC users dropped to almost single figures when we released the final PPC patches. We have not really had any requests for PPC versions of any modern games.
I would also say I have yet to find any customer who does not care about performance and would be happy with 5fps!
Why do I have to go to my 7970, 8350, AMD rig just to play games, even though a lot of people get by playing CIV V on garbage hardware that my quad core 2.5GHz, 7970 (7970 has no video output) system would destroy.
PPC machines have graphics cards from ~ 2005 which even if they were high end are now around 8 years old. Technology moves on and even if the raw performance figures in "Geek Bench" say a Quad PPC G5 Tower is as fast as a MacBook from 2010 but that does not mean it will play games or has good gfx support.
I don't care if your games come out a year later on PowerPC, all I care is that they will be there, it is never too late to reverse terrible decisions, such as not releasing games for PowerPC. Please consider doing this.
It's just not feasible for modern games, as Feral we stayed making a PPC version for as long as we could but at some point it's just not feasible. For the current games like Tropico 4 it's just not possible as the game engine makes assumptions about GL support that the PPC G5 just don't have.
We updated Rome for PPC (as we promised we would) and even though that is a massive selling game the PPC user based is tiny. The problem with PPC support is not a lack of desire to support PPC but that the machines are not capable mostly due to very old graphics support and the OS has not been updated in years.
The main things that stop PPC development being feasible are:
1. Final version of OS X for PPC Mac's is 10.5.8 - This means the port cannot use ANY new technology, OpenGL features and bug fixes in the last 4 years. When you are porting games that by design try and use every new bit of technology to the maximum that's a big deficit to overcome.
2. The best officially supported card for PPC is the X600 card in the tower. The Intel iMac (X1600) was from the same graphics series and has been unsupported (on Intel!) for almost 2 years now.
3. Due to graphics features in new games needing to use the very latest technology the minimum OS is usually 10.7.5 in games although some newer ones are 10.8.x (latest patch).
4. The PPC user base in total is under 2%, if you take into account many of these machines will be G4 and lower powered G5 machines you are left with a tiny % of machines that in theory are capable of running the games.
To summarise it's not an excuse, developing and running modern games needs modern hardware and software support. When the development is at best not feasible and worst impossible combined with fact the number of machines that might be able to play is at best under 2% of the install base it's not practical or feasible.
Edwin
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Just curious, what's been a particular challenge about Infinite, if you can speak about it? The engine/content, or political things?
I don't work for Aspyr but

based on the first 2 games in the series and a few friends who worked on the original console title I have a few ideas

Getting the BioShock engine to draw all that shiny correctly and with good performance is a real challenge and takes time, effort and some skill.
I have to admit I was slightly disappointed that I would not get to work on Infinite but equally I was slightly relieved at the same time as I knew it would be a "Big daddy" to port
Best of luck to the guys at Aspyr with the port and I look forward to playing it on release.
Edwin