Have you played every single game in your Steam library? No? Neither have I—and that accomplishment is apparently just a small sand grain in the over 288 million games in Steam collections that have never felt a press of the Play button. That's a surprising figure from a new report by Ars Technica researching the most active and popular games on Steam straight from the recorded statistics of some of the platform's 75-million-strong community.

Ars' method for its number flood involves sampling registered games and their played hours via profiles and their unique Steam IDs. With the help of a server for computational muscle, Ars randomly polled more than 100,000 profiles daily for two months to pull together an idea of which games see the most time on everyone's monitors. In other words, your Backlog of Shame (don't deny it, everyone has one) probably took part in some SCIENCE at some point. Exciting.

Some caveats exist, though. The data Ars looked at for its research only extends back to 2009, when Steam brought in its "hours played" tracking system. Owned and played/unplayed games are thus slightly skewed to not account for older releases from the early noughties, and any length of time spent in offline mode wouldn't get picked up by Steam either. Still, Ars claims its results deliver a good picture of Steam gaming trends for the past five years albeit with some imperfections.

Predictably, Valve's personal products stack high on the list in terms of ownership and most played hours. Dota 2 takes the crown with an estimated 26 million players who ganked faces at some point in the MOBA, but free-to-play FPS Team Fortress 2 follows closely behind with a little over 20 million users. Counter-Strike: Source rounds out the top three with nearly 9 million players, but it's also collecting dust in over 3 million libraries.

As for non-Valve games, Skyrim wins in activity, barely edging out Counter-Strike: Global Offensive with 5.7 million estimated active owners. Civilization V kept 5.4 million players hooked for Just One More Turn, and Garry's Mod boasts 4.6 million budding physics artists.

Want to know what the most unplayed Steam game is? It's Half-Life 2: Lost Coast, the Source tech demo given free to pretty much everyone on Steam who bought or fired up Half-Life 2. It hasn't been touched by an approximate 10.7 million players. I guess that old fisherman is feeling pretty lonely right now.

My favorite stat is the total of played hours divided by game mode, more specifically the separate multiplayer clients of the Steam versions of Call of Duty: Modern Warfare 2 and Black Ops. The single-player campaigns for each respective title sits modestly within the mid-20-hour range, but the multiplayer side balloons well into the hundreds of hours. It's a pretty obvious indicator of where the biggest chunk of popularity resides in FPS gaming, but it's not like you wouldn't get weird looks for claiming you play Call of Duty for the story anyway.

See more of Ars' results in both number and pretty orange graph form in its report .