Newt Gingrich has publicly spoken about one his favourite books of all time being Chimpanzee Politics. In that book, the primatologist Frans de Waal talks about the complex relationships that govern communities of chimps. The central point of this book is that this is part of a shared biological or evolutionary heritage we share with them - and if you want to 'win' in politics, then you need to make sure you are playing the game properly. You need to divide and rule, you need to discard manners and exchange them for a no holds barred approach, and so on. Another way of framing this would be a 'dog-eat-dog' environment.

In Julian Zelizer's book 'Burning Down The House' (2020), he attempts to pinpoint the moment that US politics shifted towards a 'bitterly partisan and ruthless' state, and he essentially draws a line in 1989, when Gingrich brought down Jim Wright, the Democratic Speaker of the House, by bringing ethical charges and accusations against him, and aggressively attacking him. This lead to him them becoming the House Minority Whip later that year, positioning him to be the leading figure in the Republican Party in the 1990s just around the corner.

There's no doubt that Gingrich changed Republican party politics. One of the biggest examples of this, are memo's that he sent through GOPAC (these days, it would be emails) throughout the 1990s, to teach Republicans how to speak like him. These memos said things like "use words like corruption, traitors, sick and radical as a way to describe your opponent". An example of one of these memos can be found here and is an interesting read as it directly and clearly shows how he essentially, took personal responsibility for training the party machine in how to 'do battle' politically speaking: https://users.wfu.edu/zulick/454/gopac.html. If you read Chimpanzee Politics and then one of these memos, you can see the direct correlation.

However, Sean M. Theriault makes a very valid point in my opinion, that Gingrich represents a 'new' type of Congressman. The 1970s were incredibly politically turbulent; obviously there is the monolith that is Watergate, which reshaped American politics entirely and the effects of it is another question - but an important one. Alongside Watergate you have the last years of Vietnam and the 'failure' in that war which checked American hegemony, as did the The Arab-Israeli War, and significant increases in international terrorism throughout the 1970s. All of these events were reshaping politics, driving more partisan behaviours, and of course, significantly impacted the next generation of politician. Theriault calls the new Republican Congressional intake of 1978 (of which Newt was part) and the intakes across the years afterwards, as 'The Gingrich Senators' (which is also the name of his book (2013)) because he sees similarities across all of them; not Gingrich as an outlier or individual force within the Republican Party. Examples include Rick Santorum, Jim DeMint, Tom Coburn and Phil Gramm. However, Gingrich was the one who rose to the top in 1989, but only did so because he was part of a large movement. In this line of thinking, it's not quite right to think that Gingrich himself reshaped American Politics, but he was simply the man who rose the top of a movement, which itself was a reaction to events.

Cause and role of the individual aside, there's no real debate about your last part of the question - whether Gingrich-led Congress 'changed the rules of the game' and there are many examples. His leadership certainly upped the ante, and changed the assumption that the 'other side' would 'play fair' by, using much more explosive language as the memo shows. Beyond this, another example was 'cam scam'. This involved delivering a speech to an empty House chamber knowing that on C-SPAN, they only had the camera on the person who was speaking so the audience couldn’t see the empty room. He could then make accusations about corrupt Democrats and when they didn't defend themselves (because they weren't even there), it made them look guilty. Some might call this innovative, others might call it outrageously misleading; but whatever your political interpretation and leanings, it (and his other behaviours) definitely 'broke the norms' very significantly. This was then combined with the Clinton Presidency post 94, where a Democrat President faced a Republican controlled Congress and Senate, with him becoming Speaker, and this gave him perhaps undue levels of power and influence for the next four years. There was then a collision between this new 'era' and political environment and two huge events that created new precedents and really showcased the new partisan politics to the entire country (and the rest of the world) - the Clinton impeachment and the 2000 contested election result. These are clearly paralleled with the Trump impeachment and the 2020 election and this is perhaps one of the key reasons his personal impact still seems so relevant today.