Doesn't the heading say 'The open source infrastructure as code tool' on loading https://opentofu.org/ ?
Edit: I don't want to sound dismissive, so let me explain the difference. Anyone coming to the website will be using a computer of some kind, and even if they for some weird reason don't, the verb "compute" does give a hint at what a computer might be. None of this is true for "infrastructure-as-code".
And I don't get why it's hidden, but instead they tell the reader multiple times it's a fork of something else.
There's a base level of knowledge of terms that's assumed on this forum. Sometimes we are below that level, and sometimes we are above it. If you encounter "infrastructure as code" tomorrow, you will not react to it the same way, since now it's no longer devoid of meaning for you.
And, in case you missed it, no one here is asking what IAC is, most everyone in this forum knows, we are saying it's not super-transparent for a random visitor to their website and a better "what is this project about" page mentioning data centers a bit more and "we forked Terraform" a couple times less would be an improvement.
Best that I found was under Docs -> intro -> What is OpenTF?:
> OpenTF is an infrastructure as code tool that lets you define both cloud and on-prem resources in human-readable configuration files that you can version, reuse, and share. You can then use a consistent workflow to provision and manage all of your infrastructure throughout its lifecycle
That could have been on the frontpage somewhere. Or in the github description.