Computer game programmer John Carmack expressed some pretty positive views on bitcoin in a series of recent tweets.

Carmack is co-founder of American video game development company id Software and is best known for his innovations in 3D graphics. He was the lead programmer of the id video games Commander Keen, Wolfenstein 3D, Doom, Quake, Rage and their sequels.

Yesterday, he was asked by a Twitter user to share his thoughts on bitcoin and other digital currencies, his response was largely positive.

@Ripper__X I have paid a little attention for a couple years, but I only did my first purchases this last month. I am guardedly excited.

— John Carmack (@ID_AA_Carmack) January 31, 2014

This wasn't the first time the CTO at gaming technology company Oculus VR has mentioned bitcoin on Twitter, back in December he revealed he had finally read Satoshi Nakamoto's original white paper on bitcoin.

The paper, titled Bitcoin: A Peer-to-Peer Electronic Cash System, was published in 2008 announcing the concept of the digital currency.

Finally read http://t.co/IKrCkQztRE . Reading the source code goes on the pile of wish-I-had-time-for projects.

— John Carmack (@ID_AA_Carmack) December 30, 2013

On 22nd January, the 43-year-old expressed his annoyance the fact the power of the bitcoin mining network is sometimes quoted in Floating-point Operations Per Second (Flops), so it can be compared with the power of supercomputers.

Earlier this week, he revealed he had donated bitcoin to The OpenBSD Foundation, which supports the development and maintenance of free software based on the OpenBSD operating system.

This is a Unix-like computer operating system descended from Berkeley Software Distribution.

He had the option to pay via PayPal, but opted instead to pay in bitcoins via BitPay.

I had a bitcoin moment recently -- wanted to give OpenBSD some money, balked at PayPal, then noticed bitcoin could be used.

— John Carmack (@ID_AA_Carmack) January 27, 2014

By donating to the foundation in bitcoin, Carmack is ensuring it doesn't lose out on any of the amount donated. If he had paid via PayPal, it's likely the foundation would have to pay a fee of between 1.4% and 3.4% on the total donation amount plus a fixed fee.

John Carmack image via Flickr.