Inclusion Criteria for Healthy Participants:  18 - 80 years of age, inclusive Normal hearing and vision, can be corrected Participants must have muscle sites appropriate for biofeedback (see below) Participants must have a minimum active flexion angle of 15 degrees and a minimum extension angle of 10 degrees. No skin allergies to adhesive material or paste No neurological disorders Absence of pathology that could cause abnormal movements of extremities (e.g., epilepsy, stroke, marked arthritis, chronic pain, musculoskeletal injuries) Able to understand and give informed consent  Inclusion Criteria for Participants Post-Stroke:  18 - 80 years of age, inclusive Normal hearing and vision, can be corrected Participants must have muscles sites appropriate for biofeedback (see below) No skin allergies to adhesive material or paste Unilateral, supratentorial ischemic or hemorrhagic stroke ≥ three months prior Participants must have a minimum active flexion angle of 15 degrees and a minimum extension angle of 10 degrees. Ability to walk >10m independently on level ground, allowed to use assistive devices or bracing as needed Self-selected walking speed is less than 0.8 meters/sec Medical clearance from primary medical team (signed Medical Clearance form) No concurrent surgeries, medical treatments, participation in research, or outpatient physical therapy Able to understand and give informed consent Able to understand and speak English  Exclusion Criteria for Healthy Participants:  Comorbid traumatic brain injury Premorbid cognitive limitations that would prevent playing games Adults unable to consent, pregnant women, children, or prisoners Implantable pacemaker, spinal stimulator, or vagal nerve stimulator Known skin allergies to silver The overlying skin on recording areas has any infection, wounds, or graft sites Potential biofeedback muscles do not have detectable electromyographic activity (this will be tested after subjects are consented and enrolled) History of sustained non-prescribed drug use (as reported by subject) or substance abuse (exception: current nicotine use is allowed) Prior neurosurgical procedures History of peripheral nerve injury Severe hip, knee, or ankle arthritis Recent fracture or osteoporosis (as reported by subject) Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures Inability or unwillingness to perform study-required activities  Exclusion Criteria for Participants Post-Stroke:  Comorbid traumatic brain injury Premorbid cognitive limitations that would prevent playing games Adults unable to consent, pregnant women, children, or prisoners Implantable pacemaker, spinal stimulator, or vagal nerve stimulator Known skin allergies to silver The overlying skin on recording areas has any infection, wounds, or graft sites Potential biofeedback muscles do not have detectable electromyographic activity (this will be tested after subjects are consented and enrolled) Botox (botulinum toxin) injection to lower limbs within the prior 3 months, or planned injection during study period Significant spasticity or contracture in the lower limbs (Modified Ashworth Scale score of 4) History of sustained non-prescribed drug (as reported by subject) use or substance abuse (exception: current nicotine use is allowed) Reduced cognitive function and unable to perform study tasks Severe aphasia Co-existence of other neurological diseases (e.g., Parkinson's disease or other neurodegenerative disorder, severe dementia, brain injury, spinal cord injury, multiple sclerosis, or cancer of the central nervous system) History of peripheral nerve injury Severe hip, knee, or ankle arthritis Recent fracture or osteoporosis (as reported by subject) Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures Inability or unwillingness to perform study-required activities