Last DOS version was 6.22, I remember having the original disks. For pure DOS games you could just stick with DOSBox then.

EDIT: Btw you can get bootdisks at bootdisk.com. And here is a direct d/l of DOS6.22 and here some other useful stuff for DOS.
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But not all games are still fully working with DOSBox so it will be useful having a proper full install of DOS just to play around with. I find some games sound gets messed up in DOSBox especially.
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