Respecting Players' Time

One thing must always be respected: the time a player invests. Players want to see meaningful progression. Resetting a player's progress breeds long-term resentment.

Roguelites get this right because each run contributes progression that carries over to subsequent runs.

The best New Game+ modes not only carry things over but also unlock entirely new content. In Dark Souls 2 there were improved versions of old items and completely new spells to unlock. In Starfield (which I know has mixed reception) you can skip parts of the main quest on a subsequent playthrough because your character canonically carries over certain choices or outcomes from a previous run.

Another good example of meta-progression is horizontal progression, often found in MMOs like Guild Wars 2 and RuneScape.

A poor example is vertical progression as implemented in some expansions of World of Warcraft: each new expansion can effectively replace older content. A player starting with a new expansion may never experience the old content, and mechanics or items can become so obsolete that their continued presence is largely meaningless.

Meta-progression is a powerful way to honor a player's time. But it is not an excuse to take things away. As a developer, always give—never take away.