TwentyOne is a Blackjack card game for the OS/2 Presentation Manager: get closer to 21 than the dealer without going over. Originally written by Michael G. Slack in 2001 (Sibyl, version 1.04). Ported to C and Open Watcom 2.0 in 2026.
1.6
GNU General Public License v3 - see doc/LICENSE.txt
- One to three decks; bet limits and start money are settings
- Hit, Stay, Double down, Split and Insurance
- 6-language interface and online help: English, Spanish, Dutch, German, French, Italian (switch at runtime in Options - Language)
- Six card backs to choose from
- Large cards (window about 960 x 640)
- Frame Controls toggle (Ctrl+F) for borderless play
- Settings saved to
TwentyOne.cfgon exit (can be switched off)
Dealer hits on 16 or less and stays on 17+. A split plays one more card on each hand. Double down only at the start (one card). Insurance (25% of the bet) when the dealer shows an ace. Five cards without going over 21 win automatically. Closest to 21 without going over wins.
| Key | Action |
|---|---|
| Ctrl+N | Play (deal a new hand) |
| H / S / D / P / I | Hit / Stay / Double / Split / Insure |
| Ctrl+Q | Quit the hand (asks first, the bet is lost) |
| Ctrl+X | Exit |
| Ctrl+F | Frame Controls on/off |
Run TwentyOne.exe. Keep the help\ folder (one .hlp per language) next to it. TwentyOne.cfg is created in the folder you start the program from.
- OpenWatcom 2.0 (
wmake,wcc386,wlink,wrc,wipfc) - OS/2 Toolkit 4.5
compile-wat.cmd
Output: bin\TwentyOne.exe and bin\help\TwentyOne_xx.hlp
- OS/2 Warp 4, eComStation, or ArcaOS
- 32-bit Presentation Manager
- Original: Michael G. Slack - 2001
- OS/2 port: OS2World community - 2026
- Card pictures: from the Compulsive Gambler cards (the original used the public domain QCard images by Stephen Murphy and Daniel Di Bacco)