RAM has nothing to do with being "future proof" it's the easiest and cheapest component you can replace. You shouldn't be restricting your choices to 16GB laptops. Some of the best laptops out right now ship with 8GB. If you need more you can add an extra 8GB card which is super cheap.
Same goes for the SSD, if a laptop doesn't come with one you can add it yourself.

The 2 best (performance/price ratio) laptops you can get right now are:
http://www.amazon.co.uk/Acer-Aspire-VN7-592G-15-6-Inch-Notebook/dp/B016B90WFG/ref=sr_1_1?ie=UTF8&qid=1449335290&sr=8-1&keywords=Acer+Aspire+VN7-592G

http://www.amazon.co.uk/Dell-Inspiron-15-7559-15-6-Inch-Notebook/dp/B0185P47QY

The graphics card is overkill according to the games you described but that's what I'd call being "future proof" in case in you decide to try more demanding games down the line.
In terms of the GPU affecting battery, the NVIDIA control panel allows you to use the integrated graphics by default and then select individually which games/applications should use the GPU.

Whatever you do, don't get a Mac, you can get much better specs for a fraction of the price.

Also, what's up with the Dell hate, everyone?

Just get the new XPS 15 (9550):

-i7
-2x SODIMM slots for up to 32GB DDR4 (atm they sell it with max 16GB only)
-USB 3.0, USB-C, Thunderbolt 3
-nVidia GTX 960M with 2GB GDDR5
-PCIE gen.3 up to 1TB SSD
-15.6 infinity display, 1920x1080 or 3840x2160
-backlit keyboard
-6cell 84WHr battery for up to 17hours

http://downloads.dell.com/Manuals/all-products/esuprt_laptop/esuprt_xps_laptop/xps-15-9550-laptop_Reference%20Guide_en-us.pdf

http://www.dell.com/us/p/xps-15-9550-laptop/pd?ref=PD_OC

Except for machines where you can't change a thing and everything is soldered to the motherboard.

As do I, but they seem to become more rare every day.
While the MacBook (just MacBook, not Pro or Air) is an extreme example, its insides look like this, remove the batteries and touchpad and you're left with this.

Nobody advises Microsoft Surface Book so far?

It is the best ultrabook out there. Except that it pricey =)

They are decent yeah but idk, its a tablet lol, I do prefer a proper keyboard in front of me
Problem is modular ones seem to have worse battery life compared to "Locked" laptops like the rMBP and I presume Dell XPS series.
Hence why I said for the Mac to get 16GB RAM, its all soldered to the logic board and the SSD is proprietary M.2 I believe, plus I don't fancy rooting about in Macs, not that I can't do it its just a simple case of I want something OOB to work :)

16GB is not "future proof", I bought my macbook 3 years ago and at that time many people already at that time on forum recommended to put 16GB to make everything "future proof", the reality is that in recent years the RAM requirements are increased, before you want to increase the RAM both cpu and gpu will already be old so you have to change computer if you want to increse performance...
So if you need 16GB of RAM now, just buy it... but if you don't need 16GB now you will not need on the future (unless you changes way of using the computer).

My experience with osx (os of the mac) is really good... I have 79 games on my gog account now, I can play all of these games on my macbook.
49 of these games are supported mac games, so I can play without do anything special,
for 29 of these games I got the wine wrapper,
for 1 games I create a windows virtual machine (the longest journey).
the first year I had installed windows on bootcamp but then I took it off (it took up space on the SSD, here, if you want to spend on something rather take a larger internal hard because change it on mac is really expensive.).
I do not know if my next computer will be a mac is (they are expensive and I do not know if I will find a compelling offer), but I'm satisfied.

For Roller Coaster Tycoon I have tried to search a wrapper on Porting Kit app ( http://portingkit.com/en/ ) that is an application to download premade wineskin wrapper... On the first try I did not find anything, but when I tried to search Rollercoaster Tycoon I find the wrapper for Rollercoaster Tycoon 1 and Rollercoaster Tycoon 2 (premade for GOG version so they have to work). In the noter for Rollercoaster Tycoon 1 I fond a note Game works at the moment Windowed only... this is the only problem you can have on mac with Rollercoaster Tycoon 1... with Rollercoaster Tycoon 2 I think there are no problem at all.
And since Rollercoaster Tycoon is not a new game it will work almost like a native mac game (and without virtual machine or bootcamp and free).

if you want to check yourself the full database of porting kit go here:
http://portingkit.com/en/database.php
if there is not a game you want to play on mac just try to find it here:
http://portingteam.com/files/
or here (click on Games first):
https://www.playonmac.com/en/supported_apps-1-0.html
or try to do a quick google search ( you can find some mac port wineskin on paulthetall.com that is not yet on portingkit app or another site)

It's not quite true. Surface Pro is a tablet. While Surface Book is not. It has detachable keyboard (one of the best by the way), but it is an ultrabook. First one from Microsoft =)
Surface Book has slightly better battery life than XPS 13 (based on reviews).

From this entire list (showed highlights)

I would say grab a MBP and use Bootcamp to get into windows for gaming only... and use OSX for your daily driver and VM's for work/other

OSX will be where you live and breath for the most part and while you can game it wont be the same as a dedicated windows machine, hence bootcamp.

Reading everything you've said it looks like a mac is your best option for current and future use... get as much ram as you can and the highest mAH bat they have. I would also suggest SSD if its an option.

XPS 13 is a better choice for you as you described above. Mac are great for design and coding. Not a good one for gaming. however, resetting dell xps password]resetting dell xps password is not a simple task if sometimes you forgot the login password. UUkeys Windows Password Mate is one of the best to do that.

Sounds more like you need a "proper" Windows laptop, but I'm quite happy with my Macbook Pro with Bootcamp. I used to run Windows 7, updated flawlessly to Windows 10, and that's what I use at work (for coding), and then OSX for pretty much everything else.

There are a few downsides though:

- Windows license cost.
- Battery lasts less in Windows.
- The damn touchpad, for some reason, is super sensitive in Windows, and while typing the cursor will jump to the mouse pointer position at the slightest touch, and sometimes not even that. I don't know what triggers it sometimes, but it's extremely annoying while coding.

Also I got quite pissed when Windows 10 removed support for HFS+ filesystem, so now you can't see your OSX partition from Windows. Only the other way round (and read-only without 3rd-party drivers to write NTFS from OSX, as far as I know).

Maybe some of these issues are fixed in newer models (mine is late 2013), but make sure to check if battery/touchpad are important for you.

Don't muck around with VM's. You can just install Win7 with Bootcamp, select your OS at boot by holding down the Option key, and get the full capabilities of your system. VM's are not nearly as fast as just running the OS natively. Anyone telling you otherwise does NOT understand the programming behind it.

The PC I'm writing this on right now is a Macbook Pro 15" and I'm in Win7 currently. Works beautifully.
I use MacDrive to access the OSx partition.

Just take a look at http://www.notebookcheck.net/ ... they have quite objective tests. Both of your choices are really nice comps, there are others like Lenovo T470s or MS Surface Book or Asus Zenbook and so on who might be interesting (but sometimes pricey).
The best advantage of the Dell XPS 13 for me is its size, compareable to 12" but still a 13" screen ;)

Here is a list of Notebooks with mechanical keyboard and non-sli graphics (best for Linux and overall less issues).