An educative game maker

Zachtronics LLC is a video game maker that was originally founded by the game designer and programmer Zach Barth. The studio is famous for its engineering puzzle and programming titles. Recently in an official announcement, Zachtronics has decided to make nearly all of its products free for public and non-profit educational institutions.

Opus Magnum
Opus Magnum - One of the games developed by Zachtronics

The list of free games includes Infinifactory (a "For Schools" version is available), Opus Magnum, Shenzhen I/O, Exapunks, and TIS-100. Their difficulty varies, from reasonably easy to moderately complicated. For example, TIS-100 (2015) is a challenging programming puzzle game where players will be "writing assembly code to repair an old computer". But the 2017 title Opus Magnum is easier to approach due to its visuals and mechanical interactions.

Infinifactory
These games are most valuable for engineers and programmers

For those who's come here because of that appealing "free games" in the title: these games are not totally for entertainment purpose. In fact, Zachtronics wanted to use them as tools to teach programming fundamentals. If engineering and programming are your favorite subjects, you can learn a lot from these games. Many programmers agreed that Zachtronics was successful in forcing them to play these games in the same way as they're working.

SHENZHEN I/O, by Zachtronics

Requirements

However, there are some notes about licensing Zachtronics' free games.

First, the developer wants to make this offer only available for public and non-profit schools. Therefore, they should be installed only on school's properties such as computers, laptops, etc).

Second, while this promotion will not be applied to regular schools and private schools, there is still a discount for them. Zachtronics also suggested that the commercial editions will be better for home-schoolers.

Last but not least: anyone who is likely to use these games for teaching should be well-aware of the gameplay.

These games are pretty hard to learn, and some of them have in-game references to violence, sex, and drugs. You can visit the official page for registration. Zachtronics has published a page full of instructions for those who're interested in its offer.