I feel like Stellaris is a measurably different game than release. I bought the game on steam like 10 years ago and while it looks largely the same, the mechanics have seemingly had complete makeovers or renovations every few years. As far as I can tell most of the modified mechanics have been introduced to the base game as well, so those without DLC aren't completely left out.

The game used to be some weird rock-paper-scissors game of either wormholes, gateways, and jump drives with corvette death columns. There was an optimal way to play and everything else was a handicap