Don't worry, Klondike runs on HTML5. We advise you to try it.
There may be some computers and operating systems that have trouble displaying HTML5 content. If you want to check whether your browser is HTML5 compatible, you can check out this site:
If your browser achieves a score of 450 points or more, then you should be fine. If not, you may want to either update your existing browser or try installing another browser.
NOTE: it is only the score you need to take note of, the details don’t matter.