Here is the design of a clinical trial:

Official Title: The Role of Video Games Therapy on Balance and Cognitive Functions in Mild to Moderate Impaired Multiple Sclerosis Patients. A Pilot Randomized Controlled Trial.

Included conditions:
- Multiple Sclerosis

Study Armgroups:
- {'label': 'Video game therapy', 'type': 'EXPERIMENTAL', 'description': 'Subjects belonging to the experimental group will receive a Video Game Therapy (VGT) protocol using the Xbox console. They will receive 12 sessions of treatment within 4 weeks (3 sessions per week); each session will last 1 hour. To manage possible absence lasting one or more treatment sessions, a potential window of 5 weeks will be set to ensure the achievement of all 12 sessions. Will be required to concentrate in games whose major purposes are increasing balance, selective attention and attention shifting. During sessions the patient will be carefully controlled by a researcher who will prevent the risk of falling', 'interventionNames': ['Device: Video game therapy']}
- {'label': 'Balance platform therapy', 'type': 'ACTIVE_COMPARATOR', 'description': 'Subjects belonging to the control group will receive the same amount of therapy (12 sessions) using a balance platform (Biodex Medical Systems, Inc., Shirley, NY). Balance/rebalancing, postural stability and weight-shifting exercises ill be administered with and without visual feedback. During the first session, the tasks will be performed at an "entry level," and the exercise progression will be adjusted over time according to the patients\' functional level (intermediate and difficult level). Balance platform therapy offered visual feedback and knowledge of performance (augmented feedback). The physiotherapist, as during VGT, provided additional external feedback.', 'interventionNames': ['Device: Balance platform therapy']}

Interventions:
- {'type': 'DEVICE', 'name': 'Video game therapy', 'description': 'Video game therapy will be delivered with a commercial video game console (X-Box 360 Kinect, Microsoft, Inc., Redmond, WA).', 'armGroupLabels': ['Video game therapy']}
- {'type': 'DEVICE', 'name': 'Balance platform therapy', 'description': 'Balance/rebalancing, postural stability and weight-shifting exercises with and without visual feedback will be administered using a balance platform (Biodex Medical Systems, Inc., Shirley, NY).', 'armGroupLabels': ['Balance platform therapy']}

Primary Outcomes:
- {'measure': 'Timed Up and Go (TUG) test', 'description': 'TUG measures balance and functional mobility.', 'timeFrame': 'Changes from baseline to end of treatment (4 weeks), following changes after 12 weeks follow up'}

Please estimate the sample size based on the assumption: 
80% power, alpha of 5%, 10% drop-out rate
Sample size and power
        The primary outcome of this study is to highlight differences in the time used to perform the TUG test between PwMS who underwent VGT and BPT. Our preliminary results from an unpublished pilot study (n=6) shown a VGT effect size of 0.93 in people with MS and EDSS <6. Given equal allocation between treatment and control arms, and using 80% power and alpha of 5%, we would need 40 subjects to complete the study. Conservatively, we expect a 10% rate of drop-out. Thus the sample size will be increased by 10% to 48 subjects (24 per arm).