Ending 1 usually feels easier once it stops being treated like a surprise cutscene and starts being treated like a rebirth checklist. The rule that matters is simple: it is tied to five total rebirth runs, and the important condition lands on the run after your fourth rebirth. On that run, at least one Item Merchant purchase has to happen before the fifth ending-clear route is finished.
That condition matters because late-game Ice Tycoon 2 progress overlaps everywhere. Gems, badges, and secret cleanup all help the rebirth cycle move faster, but none of them replace the merchant requirement for Ending 1. Finishing another full run without that purchase can still make the save stronger, but it can also leave the ending branch unfinished. That is why Ending 1 usually goes better when the qualifying run is planned before it starts.
The early rebirths tend to feel better when they stay practical. Use them to complete the tycoon, make the economy sturdier, and pick up long-term bonuses such as gems or useful hidden progress if those routes are already close. By the time the fourth rebirth is done, the fifth run should feel more like staying organized than barely surviving. That is also why Ending 1 usually lands better as the first ending attempt. It matches the normal "build, reset, build faster" rhythm instead of pushing against it.
Once the qualifying run begins, the merchant step feels best when it happens early enough to stop being a worry. Buy at least one Item Merchant item, then let the rest of the run stay clean. Rebuild the production line, finish the tycoon path, and leave side cleanup alone unless it is already almost done. Ending runs usually feel smoother when there are fewer optional decisions floating around.
If the save still feels weak, forcing Ending 1 too early is usually what makes it sloppy. A thin economy slows the fifth run down, and a slow fifth run makes it easier to forget the one condition that actually matters. The route feels much better once permanent bonuses and rebirth multipliers already make the cycle comfortable.
Ending 1 usually works best as the standard branch that proves the rebirth loop is under control. Count the rebirths carefully, get the Item Merchant purchase on the post-fourth-rebirth run, and finish that fifth cycle cleanly. That tends to feel much better than trying to improvise the condition at the last minute.