The blade template engine can be used with codeigniter?
Blade can be used stand-alone in PHP.
This means you can comfortably use it in CodeIgniter.
https://github.com/PhiloNL/Laravel-Blade
Then again, you will need composer for that.
Alternatively you could use this CodeIgniter Library to simulate Blade: CodeIgniter Slice-Libray
It works pretty like Blade and it was designed directly for CodeIgniter!
For the record and as answer to another post:
I tested many libraries to run blade outside Laravel (that i don't use) and most (with all respect of the coders) are poor hacks of the original library that simply copied and pasted the code and removed some dependencies yet it retains a lot of dependencies of Laravel.
I created an alternative for blade that its free (MIT license, i.e. close source/private code is OK) in a single file and without a single dependency of an external library. You could download the class and start using it, or you could install via composes (composer require eftec/bladeone). So even composer is optional.
https://github.com/EFTEC/BladeOne
https://packagist.org/packages/eftec/bladeone
Its 100% compatible sans the Laravel's own features (extensions).