1. A training program comprising a combination of games configured to systematically drive neurological changes to treat major depressive disorder (MDD), the training program comprising: a plurality of computerized processing speed, attention, and executive functioning games configured to treat different cognitive impairments associated with MDD, the plurality of games including: a processing speed game that serves visual and/or auditory stimuli, wherein the processing speed game is effective in upregulating activities in cerebral attention networks that are impaired in a game participant diagnosed with MDD; an executive task game that is effective in improving executive functioning in a game participant diagnosed with MDD; and an inference renormalization game configured to: present a plurality of stimuli, a subset of which are positively affective, a second subset of which are negatively affective, and a third subset of which are neutral; prompt a game participant to respond to both the positively affective stimuli and the negatively affective stimuli and refrain from responding to the neutral stimuli; receive the game participant's input through a game piece; provide an indication to the game participant of whether the game participant's input was accurate; and repeat the presenting through providing an indication steps over multiple repetitions while adapting one or more difficulty parameters to target maintenance of a success rate within a predetermined range.