Not exactly what you asked, but close I think: a (paid) full gamified typing course for kids, in several languages including English: https://www.typetopia.com/

Just updated apps on my phone. Appears to be doing three updates at once. Still, a huge improvement.

You are wrong, till is perfectly fine – and so is til. See Merriam-Websters article about this, at https://www.merriam-webster.com/grammar/should-you-use-until-or-till-or-til