Not Thinking With Portals - What are my game design principals?

This post is included for posterity. It was originally posted in my now-defunct Discord server.

I have learned that as much as physics-driven / single mechanic-driven games sound fun and elegant to make, the game mechanic alone is not interesting for me to grind out a game. In the case of the Portal series, for example, the compelling narrative carried me through. In the spirit of making a game I want to play, I am taking the time to reflect on principles that make a game fun for me.

Time is valuable

• 2 steps forward, 1 step back;
• Short term gains can be lost, long term progress / impact should be everlasting in some form.
• Short term loss can make the gains more meaningful by ensuring that they were not gained by chance. Doing something right consistently is rewarding instead of just relieving to get through the first time. For this reason, checkpoints should not be too often or insuring.
• Your strengths influence what you can do, but what you do should also influence your strengths.
• Changing focus/build should feel lateral, meaning being able to prepare what will be gained before having to lose anything. Whilst a different approach might not work out, the player should not be punished (in time) just for trying to experiment.
• If an item's value is transient - make the effort one of decision making and not grinding.
• Grinding is OK for items with implicit value/application.
• If I have spent time grinding to achieve a goal, the reward should provide an obvious advantage and not be a compromise.
• Statistical improvements should make you feel stronger. No point just necessitating stat checks to proceed through the game- should feel like it is empowering instead of playing catch-up. E.g. Allow visiting old areas/killing the early enemies later on in the game.

Rules of engagement should not be exploited against the player

• Physics create nigh-on-unfixable edge cases which make it hard to pin core game-play to whilst maintaining depth. This is evidenced by some of the most frustrating behaviour in challenging games being due to inconsistent physics.
• Cheese / exploits are mechanics that completely circumvent another mechanic due to their superiority. Usually unintended by the developer as for it to be intended is a sign of bad game design, but they are often left unfixed as a sign of bad quality assurance. This is usually fine in a single-player game as the average player will never run into them, but is a crime in PV.
• In PVE, cheese / exploits are OK because it rewards ingenuity. It provides a mirror to encourage innovation in what otherwise would be a static environment (not including RNG).
• Opponent player(s) can be rewarding to go against even when the rules of engagement are known because of their own creativity. Cheese is frustrating in PVP because your agreed-upon rules of engagement are being compromised by your opponent.
• Cheese can be a great way to alleviate, grind both through direct efficiency reducing the need to perform a repetitive task, and the player getting to demonstrate a skill. Don't let the best gameplay or part most important to narrative be cheesed!

I hope these principals, among others, will help guide me to avoid wasting my own time when developing a gameplay concept past the initial prototype.