Полигон-2

Так первый Monkey Island, первые Goblins, Budokan, Barbarian, Future Wars (квест, но на геркулесе играть трудновато),
Metal Mutant, BlockOut (3D Tetris про который alecv упомянул)... ну если будет мало, еще что-нибудь подберем))
Для Golden Axe нужно небольшой патчик, в оригинальном файле баг имеется.
А демо есть такое - называется Three Shades Of Gray by Alumni, можно его, например.

Эмуляторов CGA на Hercules было штук 5 разных и довольно много CGA-шных игрушек шло под эмуляторами, но надо было подбирать эмулятор под игруху. Некоторые не работали, некоторые работали странно, иногда было видно как видео-память переписывается кусками (из B800 в B000)

640x400 для HGC, режим с более адекватным "aspect ratio"
    []---------------------------------------------[]
    |            |
    |  HGC 640/400 mono mode description  |
    |            |
    |       Version 1.00      |
    |        Copyright © 1996 by    |
    |      Wojciech Migda    |
    |            |
    []=============================================[]

  HOW WAS IT INVENTED ?
  ~~~~~~~~~~~~~~~~~~~~~
  Several times I was working on my old HGC trying to get more
  than was offered in standard documentations hoping to get
  better graphics. I Paid the main attention to CRT registers.
  In all descriptions I've read was written that CRT register
  number 8 MUST contain 02h. So I tried to write there something
  else. Bingo! The magic number was 3. In text mode vertical size
  of the screen was decreased and there were horizontal black
  lines between every text line. I had to subtract 1 from the
  letter size to get rid of them. In assembler it looks like
  that:
    mov  dx,03b4
    mov  ax,0308
    out  dx,al
    mov  al,ah
    inc  dx
    out  dx,al
    dec  dx
    mov  ax,0c09
    out  dx,al
    mov  al,ah
    inc  dx
    out  dx,al
  Done. Hmm.. we have the same number of lines like before and
  a lot of free place above and below them. We could increase
  the number of lines like with VGA card, but because of the
  constant size of the memory page equal 1000h the screen is
  being wrapped. If you know how to change it please tell me
  (my adress at the end of this doc).
  Then I tried to do the same in the graphics mode 720/348. It
  changed the size of the screen too, but I couldn't recognize
  the memory structure. Finally I discovered that like in the
  text mode I needed to decrease content of the #09 register
  which in text mode means height of letters but in graphics mode
  it contains number of memory banks. The result was 640/400 mode.
  It could have more lines but it is limited by the memory page
  size equal 8000h, so maximum lines number is 409.

  HOW TO TURN IT ON ?
  ~~~~~~~~~~~~~~~~~~~
  Below are numbers (in hex) that must be written to CRT registers
  to turn this mode on:

  INDEX:    | 00  01  02  03  04  05  06  07  08  09
  ----------+----------------------------------------
  CONTENTS: | 37  28  2d  07  68  1f  64  64  03  02

  Memory is divided into 4 banks like in the 720/348 mode, but
  the line size is equal 80 bytes. Every byte codes 8 pixels and
  so on.

  IS THIS CODE FREE ?
  ~~~~~~~~~~~~~~~~~~~
  Yes, if the program which includes it is free too. Otherwise
  you are obliged to send me 5 USD. Also nice postcards are
  welcome.

  HOW TO CONTACT THE AUTOR ?
  ~~~~~~~~~~~~~~~~~~~~~~~~~~
  I can be reached under following adresses:
    E-mail:
      cooker@august.v-lo.krakow.pl
    Snail-mail:
      Wojciech Migda
      os. Piastўw 23/41
      31-624 Krakўw
      POLAND
Из софта есть относительно современный вьюер картинок CompuShow 2000! от Canyon State Systems. Можно слайдшоу запустить. Он, кстати, вроде умеет недокументированный 160x100x16 для CGA, всякие SuperEGA умеет с 640x480x16 и ещё много чего. Я его патчил на run-time-error на современных машинах и на лимит по XMS/EMS памяти.