I think anyone should be able to get to the Posit Science BrainHQ Daily Spark exercises. At least, the e-mail states,
Every weekday, the Daily Spark opens one level of a BrainHQ exercise to all visitors. Play it once to get the feel of it — then again to do your best. Come back the next day for a new level in a different exercise!
If you try and can get to them without paying (even better if without registering), let me know. Or let me know if you can't. Since I have a subscription, I'm not sure what others see.
I find the BrainHQ exercises interesting and challenging, and I really have to get back to doing them on a regular basis.... (95 by 65 goal #70)
