Absolutely! The Tactus Therapy apps are designed to be used with only a simple touch/tap gesture.
It is recommended that the apps used by stroke survivors are displayed on a screen large enough to see and touch easily (full-size iPad/tablet recommended over phone or mini options).
For one-handed use, the tablet should be placed on a flat surface, such a table or lap, and may best be positioned at a slight angle on a stand or folding case to avoid glare from overhead lights. Those able to use two hands will likely benefit from this position as well, though they can use one hand to hold the device (usually a phone or mini tablet) and the other to select the answer.
There are a few apps that make use of a swipe, pinch, and drag gesture. All of these can be done one-handed as well, and they are not required gestures.