Block game download from ads

How do I keep a senior citizen from downloading and installing every game from ads that pop up from games that are installed? He has a few games he likes and ads pop up and he cannot be told about the X in the corner to keep from installing them. His memory is a factor. I need a block of some sort. Every day that he plays, he has five more new games installed. I need ad-free solitaire, mahjong, and pyramid solitaire, and he likes Bejeweled. Does anyone get any ideas? And YES.. we have shown and told him not to. It is forgotten.