What video game has the smallest amount of players and is free?
select ?ent where { ?ent wdt:P31 wd:Q21125433 . ?ent wdt:P1873 ?obj . ?ent wdt:P31 wd:Q21125433} ORDER BY ASC(?obj)LIMIT 5 
free or open-source video game: Q21125433 free or open-source video game: Q21125433