I-Deas is still alive and supported. Lastest version is NX I-Deas 6.8 , I-Deas has been Windows 10 compatible since NX 6.6
Hasn't been any significant new functionality since NX I-Deas 6.0 released back in 2008. Updates since only for licensing/operating system compatibility.
It's not activly sold, Siemens have been encouraging all I-Deas users to move to NX (Unigraphcs) for the last 20 years ! but speak to Siemens or your local VAR and I'm sure they will sell you a copy, we bought a license in 2019 to support legacy data.
Easiest option would probably be to buy a license of NX, you can run I-Deas against an NX license.
Cheers
Neil