DetectiveOS vs Cold Case Inc: Which Online Case File Should You Play?

DetectiveOS and Cold Case Inc both put a murder case file in your browser and leave the solving to you. If you're choosing between them, the differences are in the details: how big a case is, what you do besides reading, what it costs and how you can try it first.

We make DetectiveOS, so read this with that in mind. Everything about Cold Case Inc below comes from its own website, checked in October 2026, and prices can change. DetectiveOS isn't affiliated with Cold Case Inc.

Side by side

What Cold Case Inc does well

Cold Case Inc is a classic cold case file done properly. You get a folder of evidence, you read it closely and you work out what happened, the way you would with a printed case on the kitchen table. Its cases range from about an hour for the easy ones to four hours for the hardest, so there's a long one if you want a whole weekend afternoon, and some cases come with printable files if you like paper in your hands. The free case, Flat 33, is a 10 to 12 minute taste of how it works.

What DetectiveOS does differently

DetectiveOS gives you the case file too, and then puts you to work on it. Its signature is the interrogation room: suspects answer written question cards (ask straight, gently, press or bluff), and when one lies, you point at the exact line and prove it with the evidence that breaks it. The evidence fights back as well: a voicemail buried under a hum you have to filter out, a photo hiding a second image, an inbox you need a password for, a money trail to follow.

When you think you know who did it, you file charges with your evidence. A wrong charge comes back to you, and every lead has sealed tip envelopes, from a gentle nudge to one that spells out the next step, so you don't get stuck for good.

The free case is a whole case rather than a sample: Speak Now, a bride stabbed before her midnight toast, with four suspects and two lies to catch. Most players finish it in about an hour.

Price

A single case costs about the same: $7.99 for DetectiveOS, £9.99 for Cold Case Inc (which runs sales). The difference is in buying more than one. DetectiveOS sells any three cases for $16.99 and all 8 for $35.99, about $4.50 a case; Cold Case Inc sells cases one at a time. Both are one-time purchases with no subscription.

Who should pick which

• Pick Cold Case Inc if you love reading a classic cold case file, want the option of a very long case or printable pages.
• Pick DetectiveOS if you want to question the suspects yourself and catch them lying, use forensic tools on the evidence, and get a whole free case to decide with.
• Can't decide? Both have a free case. Play Flat 33 and Speak Now on the same evening and see which one you want more of.

Questions

Is either of them free?

Both let you start free. DetectiveOS has Speak Now, a full case of about an hour, with a free account and no card. Cold Case Inc has Flat 33, a 10 to 12 minute mini case, sent to your email as a sign-in link.

Can I play on my phone?

DetectiveOS reads fine on a phone, but handing in evidence needs a laptop or desktop. Cold Case Inc plays in the browser; check its site for what works best on your device.

Can two people play together?

Yes, both. Cold Case Inc says its cases can be solved by two people sharing a screen. DetectiveOS works on one laptop on the sofa or shared on a video call. See DetectiveOS for couples.

Want more options?

See our lists of the best online detective games and free online detective games.