Yes, you can still use a normal timer. It's one of the first things mentioned in the post.

Bloons Tower Defense 6

TL;DR - new mod for timing, files are in resources tab

Hi everyone,
Just wanted to let you know that we are introducing a new timing system involving a mod by Minecool. This mod does not affect gameplay in any way, and OTHER MODS STILL REMAIN BANNED. Instructions will follow on how to set this mod up, and files linking to the mod will be sent in the resources tab of our leaderboard page. 

**Older timing methods will still be valid, and those who do not choose to use the mod can still submit runs just as before.**

A few reasons why we wanted to introduce this system: 
- The pause bug has been around for way over a year now, and it doesn't look like it's going away any time soon. This mod takes pauses into account and automatically removes them
- Hardware differences have been making a huge difference at the top level up until this point, it seems that the mod will either eliminate them entirely or at least significantly reduce them
- It makes it so much easier to keep track of how fast your runs are because you get told how fast each round is during the run.

About how the mod works: 
- The timer only works on PC for now.
- The mod does not require any other mod files, except MelonLoader, which will be attached along with the mod itself.
- There are two versions of the mod, one that makes time go up constantly, and the other that only updates every round. Either may be used, however in category extensions (where timing doesn't end on the end of a round), the continuous timer must be used.
- The 'upgrades' button in the top-right or bottom-left of your screen gets replaced with the timer
- Every frame of slow time (i.e. when the game is going but not on fast forward) will lose 2 frames (~0.011 as we now time based on a 180fps standard)

How to add the mod to your game (this link contains similar instructions with pictures - https://hemisemidemipresent.github.io/btd6-modding-tutorial/) :
- Download the MelonLoader .zip from the resources tab
- Download https://dotnet.microsoft.com/en-us/download/dotnet/thank-you/runtime-6.0.12-windows-x64-installer and install it
- Take all the files into C:\Program Files (x86)\Steam\steamapps\common\Bloons TD6
- Open the game to make the "Mods" folder appear in the same location as above. If you get an error, you might need to install virtual C++ and restart your computer: https://aka.ms/vs/16/release/vc_resist.x64.exe
- Download the .dll of the mod of your choosing from the resources tab
- Put this into the mods folder
- Open up the game, and the timer should be working

Timer in action: https://youtu.be/x2VGPPv39LA 

The mod has been in pre-testing for a few days and has received positive results throughout, so we hope that this introduction will make getting top times easier. If anyone has problems working out how to use the mod, let me know on discord or on this website. Hope to see some runs from everyone soon!

~SummerPi and the BTD6 mod team

P.S. Category Extensions wave 2 coming soon