Retro-style game design is something that requires some knowledge of history. Just making something low quality doesn’t work. Even if your game is low-resolution and has a limited set of colors, it may not look like a retro game. I made some games using QBASIC, but that didn’t necessarily make them good. There were good aspects to them, but more design, art, and programming would be needed to make the games have broad appeal and replayability. Many retro games have a great deal of depth and culture behind them.
Consider Dragon Warrior for NES (Dragon Quest I). It is one of the most graphically primitive among IGN’s top 10 NES games (especially in the tilesets and animation), but incorporates themes from very old European stories (even though the game was made in Japan). This shows that the authors either did a large amount of research or already had in-depth knowledge of cultures outside of their own. Even the English translators working for Enix used Elizabethan English (the language of Shakespeare) to translate from Japanese, however with modern spelling and mostly modern nouns.
This is where some clarification about number of bits is needed. The NES has an 8-bit processor, but can only display 13 colors at a time (unless per-tile palette swapping is done), making its graphics often (especially when programmers lacked skills or budget) more like what computer experts of the time would call 4-bit (16-color). Similarly, though the SNES is 16-bit, the number of colors displayed at the same time generally max out 256, something like 8-bit color (not to be confused with 8-bits per channel “True color,” or greater for “HDR”–#-bit terminology is sometimes used when discussing photo or video editing, but in the case of bits per channel would generally be multiplied by 3 for red, green, and blue to get the total bit depth). The reason for this pattern is that not all of the processing power goes into processing graphics palette entries. If you continue up the scale of number of bits on consoles, you will see a similar pattern. This is why early “32-bit” or “64-bit” (or higher) consoles didn’t look much different from competing consoles or even previous generations.
When people say that they want to make an 8-bit game, or retro game, they usually mean they want to make a retro-style, retro-themed, or otherwise lo-fi (intentionally low fidelity) game. The term “retro game” has become a synonym for retro-style games, though technically retro games are actually the old games that inspired the modern games that have retro-style graphics, sound, or themes. These newer retro-style games often use new technologies with the pixel art style and sometimes low-fi synthesized music in order to recreate the experience of retro games without the limitations, which are more glaring upon replay than in players’ memories (due to lack of processing power, programmer skills, or budget for effects as simple as rotation or particles in the case of many 2D consoles). There are many examples of great retro-themed games which do recreate the experience while surpassing the limitations, notably Undertale and Shovel Knight, but there are many others which can be found in Steam’s most popular games list, and “top retro games” lists (or lists using related keywords, such as “Hi-Bit Era – The Future of Pixel Art Games // HeavyEyed“) on YouTube and other websites. For more explanation on using pixel art techniques with modern technology vs. early graphics technology, you can watch “8 Bit & ‘8 Bitish’ Graphics-Outside the Box” on YouTube (Mark Ferrari’s presentation at GDC 2016). Simply copying the technology of the past doesn’t create the same feeling of playing a retro game as your first game (especially without recreating or inventing advanced tricks to work around limitations, which the creators of Micro Mages managed to accomplish), but drawing upon your knowledge, experiences, and inspirations will always help you make your game stand out in quality and even uniqueness.