Capcom has left fans stumped as it has mysteriously delisted Devil May Cry 3 and 4 on Steam. No reason was given by the publisher/developer, but SteamDB has claimed that pair of titles were "retired at the publisher's request."
Luckily, there is still a way to play both of these titles on the platform. Devil May Cry 3 is accessible through the Devil May Cry HD Collection and the Special Edition of Devil May Cry 4 is still available for purchase.
Whilst there is fortunately a way to still play these games on Steam, its still frustrating that Capcom has removed the most cost-effective ways to play them.