YOU are standing on one of the few unburnt hillocks of grass outside Belching Bloodfire grotto. Around you, you can see the bleached skeletons and the warped and curling breastplates of a score of knights errant, lightly flambéed inside their full plate. From the darkness of the cave, you can just hear the sound of an unthinkably massive, scaled creature shifting its weight against the cavern’s floor.

Do you (a) pick up a rock and lob it at the cavern’s entrance? Do you (b) take the opportunity of all the scorched, meatless bones and skulls around you to practise the drum solo you’ve been working on? Or alternatively, do you (c) go back the way you came in a calm and orderly fashion, and seriously consider alternative New Year holiday destinations next December? Please turn to page 39.

If you chose path (a) or path (b) – the bad news is your adventure is now over. But on the plus side, your family won’t have to shell out for a cremation. Players who chose path (c) should turn to page 54 and decide whether they arranged an appointment with their GP about the rumbling disquiet they detected in their colon as they beat a hasty retreat from the dragon’s desolation. Updated health statistics and Barnett consequentials to follow.

Choose-your-own-adventure books were a fixture of my childhood. Within the four corners of the story, you – our hero – picked your course of action. Some outcomes were happy, others considerably less so. You cheated, of course. Well, I cheated. Thumbing forward to the consequences before making my choices, and turning back when a promising path turned out to be a lethal cul de sac. Often as not, you ended up screaming in a dragon’s belly anyway.

In retro telly terms, CITV’s late 1980s classic Knightmare brought the puzzle and jeopardy of the dungeon adventure to the small screen.

But the idea of fixed moments in your timeline which change everything is familiar fodder from everything from Sliding Doors to Doctor Who. We’ve all got our roads less travelled. The party we didn’t go to. The person we didn’t meet. It is amazing how much of life’s happiness and unhappiness is down the navigation of chance encounters.

Since I was a nipper, a new generation of role-playing games have kicked the choose-your-own-adventure genre up a notch. The best and bleakest of these – such as the Witcher series – recognise at least three essential truths. One: every decision has its consequences, and these consequences aren’t always predictable. Two? Even if your actions and inactions are guided by the best of intentions, their consequences can be pretty dreadful. Third? You can’t please all the people all of the time.

In environments with complex and competing interests in play, to curry favour with one side is almost inevitably to wind up some other guy. In your efforts to please everyone, you risks pleasing no-one, alienating friends and enemies alike, and achieving nothing.

This may all strike you as gloriously geeky. But reading this weekend that Netflix’s latest Black Mirror sees its audience determine the big choices made by Bandersnatch’s protagonist made me think about the merits of projecting our politics through the lens of the choose-your-own-adventure genre. There are less sophisticated ways of thinking through where 2018 leaves us.

You can swizz a book. You can fire up a saved game if you’ve made a pig’s ear of your choices. But real life isn’t so easily cheated or reloaded. We can wargame political options as they confront us and try to take rational choices. We can peer back in retrospect, try to learn from our experiences, and speculate about what we might have done differently. But in real life, our earlier choices are baked in.

“If I were you, I wouldn’t start from here” is a good gag – but it only works because the lost traveller has no alternative but to trudge on from where they find themselves. At the close of 2018, British politics finds itself ankle-deep in its past decisions, struggling to navigate the mire.

2019 already looks like a year of conditional sentences – of if/then thinking with a whole host of imponderables still in play.

Take one example. Not for want of effort on the part of the Scottish Government, one of the major failures of UK politics since 2016 has been to pull together a cross-party coalition in the House of Commons for the gentlest Brexit possible. Theresa May has been left to it. Her unloved and unlovely deal with Brussels is the consequence of the initiative she retained. This looks like an opportunity missed.

But wargame the outcomes. Say, for the sake of argument, a broad, cross-party approach to Brexit had been assembled at some point over the past 12 months. This would make Britain’s departure from the EU a considerably surer thing than it now appears. If your main priority is stymieing Brexit altogether, then that missing coalition for an underanged Brexit helps justify a second vote.

It’s high wire stuff and a reminder, as if you needed one, that politics is a tricksy business.

2018 ends with a score of outstanding counterfactuals. Will Theresa May’s deal pass its Commons test in January? If it fails, then what? Will there be (a) no deal, or (b) a second vote on the UK’s EU membership, or a delay leading to either (a) or (b) further down the line? Take just one of these alternative timelines – and the counterfactuals continue to multiply. Say there is a second referendum on the UK’s place in Europe. What happens next?

Given the chance to revisit 2016’s vote, would a majority of the British people change their minds, or double down on the earlier choice to leave? If a majority decided to remain in the EU we know – thanks to Andy Wightman and Joanna Cherry – that the UK has the right to recall its Article 50 letter. But if a majority continues to back leaving the EU, then where are we?

In the Scottish context, it has gradually dawned on folk that if the trigger for a second independence referendum is “being dragged out of the EU against our will” – not leaving the EU would seem to reset that particular trigger. For people who prioritise independence at any cost, in any context, on any argument – this might make the First Minister’s position a little confusing. Why is Nicola Sturgeon trying to trim the fuse as it is burning down?

This has, perversely, encouraged some independence supporters to conclude that the best outcome possible is a no-deal Brexit, as it seems to pave the way for a second independence referendum. As this column has tried to sketch out over the last couple of months, this subplot isn’t nearly as simple as its proponents maintain.

For starters, the First Minister’s manoeuvres are trying to give effect to the vote Scots cast in 2016 to stay in the EU. A no deal Brexit seems certain to inflict considerable damage on the Scottish economy but the polling suggests it is the outcome which – in a short-term political sense – is likely to drive more Scots into the independence camp.

On the other hand, if the UK finds itself resorting to World Trade Organisation rules for its European trade and custom checks on the Northern Irish border, this generates a powerful series of new challenges for a Scottish nationalism which wants to remain in the European Union. In this scenario, independence-supporters would have to consider – and justify to the Scottish people – how a border with England could and would operate.

Once we’ve tackled that, we can turn to the import and export figures. But scooch back a few pages, accept something like Theresa May’s deal, avoid a hard Brexit, or avoid Brexit altogether and this scenario need not materialise.

The politics of 2019 isn’t an adventure for folk who like black-and-white thinking. Here be dragons. Big ones. Wee ones. Lots of them. Wherever you are politically, right or left, on the constitution – there is no dragonless territory.